Troubleshooting¶
Common issues and how to fix them.
Tender's Backend Won't Start¶
Connection shows "Backend error"¶
Symptom: The Tender QAM panel's Connection row shows a "Backend error" badge with the note "Tender's backend failed to start — check its log", and the Sync buttons are disabled. This state means Tender's own backend process never started — it is not the same as an unreachable RomM server, which shows Not connected instead.
Fix: The backend aborted during startup, so the panel can't reach it. Its log says why:
Then start it again:
If it still fails, restart Steam (or the Steam Deck); if the error persists, include the log output when you report it.
Reaching that verdict takes up to about a minute and a half, because the check keeps retrying to ride out a backend that is merely slow to start rather than calling it dead too early. It runs to its conclusion whether or not the panel is open, so you do not have to sit and watch it — close the QAM and reopen it later, and the row shows the answer. While a check is running, the row keeps showing the previous result rather than resetting to Checking….
Sign-in reports "Tender's backend never answered"¶
Symptom: The Sign in to RomM dialog sits on Signing in… for a minute and then shows "Tender's backend never answered. Restart it, or restart Steam, then try again."
Fix: The dialog reached Tender's backend process and got no reply at all, which normally means the backend is no
longer running — the panel itself keeps working because its code is already loaded in Steam. Start it again with
systemctl --user restart romm-tender, or restart Steam, then sign in again. A pairing code is single-use and expires
after 60 seconds, so generate a fresh one for the retry.
This message is specific to Tender's backend being unreachable. A RomM server that is merely down or misconfigured answers with its own message instead — "Server unreachable", "Sign-in rejected", or the RomM version notice.
Steam's Screen Reloads by Itself After a Backend Restart¶
Symptom: Shortly after Tender's backend restarts — after systemctl --user restart romm-tender, a reinstall, or the
backend starting again by itself — Steam's interface disappears for a moment and comes back, and Tender's panel returns
a few seconds later. If a game was running, this happens after you exit it.
Explanation: Nothing is wrong. The panel still in Steam belonged to the backend that just stopped, and it cannot talk to the new one, so the new backend asks Steam to reload its interface once to put a fresh panel in. It waits while a game is running. If Steam cannot reload, or the old panel is still there after the reload, it restarts part of Steam once, which takes the interface away for a few more seconds.
Fix: If no game is running and a few minutes later Tender's panel is still missing, or its section on a game page still says "Loading...", restart Steam to load the new panel. The backend tries only once after each backend restart, and it takes Steam's interface away no more than twice in ten minutes. The log says what was tried:
A WARNING line that says "Restart Steam to load" means the backend has stopped trying. Not every case leaves one — the backend may still be waiting because it cannot tell whether a game is running, or Steam's interface reloaded and the old panel went with it but the new one did not arrive — so the missing panel, not that line, is the reason to restart Steam.
An Update Was Rolled Back¶
Symptom: An update marks the Service row failed, says Rolled back instead of Done, and ends with
install.sh: update to <new> failed; back on <previous> and a line pointing at the log and at the journal.
Explanation: The new version did not start within about a minute, so the installer put the version you had back,
together with the library database and settings it had before the update, and started it again. Tender is running as it
was. Anything the new version wrote in that minute is gone. The installer does not try again by itself, and it leaves
~/.local/state/romm-tender/update-failure.json naming both versions and the time.
Fix: Look at what the new version logged — the log is shared by both versions, so the lines just before the previous version's start are the new version's. A version that failed before it could open its log left nothing there, and its reason is only in the journal:
Include that when you report it. Running the installer again tries the update again.
Going back to the previous version by hand¶
If an update did start but you want the version before it back, the installed copy of the installer does that:
It puts back the previous version and the database and settings as they were before the update, and says the date
that was. Anything Tender recorded since, such as a download or a sync, is forgotten: ROM files downloaded since stay on
disk and shortcuts created since stay in Steam, but the restored database no longer knows them. Before it puts anything
back, it copies the database and settings it replaces to ~/.local/share/romm-tender/rollback-backup/, and it says so.
That copy stays until the next time you go back by hand.
It works once per update — afterwards there is no previous version left to go back to — and refuses without changing
anything when there is nothing to go back to. It also refuses when the previous version and the saved data do not belong
together, which an update that was interrupted can leave behind: going back would run the older version over data a
newer one wrote. Start Tender instead if it is not running, with systemctl --user start romm-tender.
Games Won't Launch¶
"RomM Sync" is still installed¶
Symptom: Decky lists two plugins — an older RomM Sync and Tender. Tender may also look brand new, with no server configured and no synced games.
Fix: Nothing to fix, but do not remove the older plugin until you have checked one of your games. Your shortcuts may still start through a file inside that older plugin's folder; removing it before they have been repointed stops all of your games from starting, and nothing can put that file back. A game's own Target path tells you which state you are in — see Updating from a release before 0.31.0 for the check and what each answer means.
BIOS files missing¶
Symptom: A game for a system that requires BIOS files (PlayStation, Saturn, Dreamcast, etc.) fails to launch or shows a black screen.
Fix: Check the game's detail page — if the BIOS indicator is orange, you're missing required BIOS files. Open Library › Platforms in the QAM, pick the platform, and tap Download all. See BIOS Management for details.
ROM not downloaded¶
Symptom: Pressing Play does nothing, or you get a toast saying the ROM needs to be downloaded.
Fix: Open the game's detail page and tap Download in the Tender panel. The game will be playable once the download completes.
The download has no launchable file¶
Symptom: The download finished, but pressing Play shows a toast saying the download has no file the emulator can launch. The game's detail page repeats it under ROM File.
What happened: Some titles are distributed as an installer rather than as playable content. The clearest case is a
PS3 game shipped as a .pkg (plus a .rap licence file): the game is sealed inside the package until an emulator
installs it, so there is nothing for a shortcut to launch. The same applies to a disc rip that arrived as raw .bin
tracks with no .cue or .gdi alongside them.
Rather than write a launch command that cannot work, the plugin leaves the shortcut without one and says so. Your download is not deleted — the files are on disk exactly where the ROM would normally live.
Fix: Install the content in the emulator yourself. For a PS3 .pkg, that is RetroDECK's documented procedure — open
RetroDECK → Configurator → Open Emulator → RPCS3, use File → Install Packages (PKG), point it at the downloaded
.pkg, and install the .rap licence the same way. Launching from Steam once a package is installed is not supported
yet; start it from RPCS3 in the meantime.
To find the files, open the game's detail page — the ROM File section shows the filename the download produced.
Controller doesn't work in RetroArch menus¶
Symptom: The game plays fine, but the RetroArch Quick Menu (L3+R3) can't be navigated with the controller — only mouse/touch works.
Fix: This is caused by RetroArch using the x input driver on a Wayland system. If the plugin detects this, a
warning appears on the main QAM page with a Change to sdl2 button. Tap it to fix the issue.
If the warning doesn't appear, you can manually change input_driver = "x" to input_driver = "sdl2" in your RetroArch
config file.
Saves Not Syncing¶
Auto-sync is disabled¶
Fix: Go to Save Sync in the QAM and make sure both "Sync before launch" and "Sync after exit" are toggled on.
Server unreachable¶
Symptom: Toast notifications say "RomM unreachable" or sync operations show in the Failed Syncs list.
Fix: Check your network connection and verify the RomM server is running. The Connection row on the plugin's main QAM panel shows the live status (and names the problem when it can't connect). Failed syncs are queued and retried automatically when the server is reachable again.
Offline detection and recovery¶
When the plugin can't reach RomM, it notices from the calls that fail (a connection probe, a save-status or slot load, a version switch, or the first-time save-slot setup) and marks itself offline. On a game's detail page you'll see a RomM offline badge in the play row, the Download button and slot switching are disabled (they need the server), and the Saves tab shows a "RomM is offline" banner and renders straight away instead of hanging. The Achievements tab does the same — it shows a short "RomM offline — achievements unavailable." line (keeping any list and counts it had already loaded) instead of spinning on "Loading achievements…" forever. The first-time save-slot setup screen also shows its "RomM server is not reachable" message and a Retry button immediately rather than working through the connection attempts. Playtime keeps showing — it's tracked locally and doesn't depend on the connection.
While a save load is actually reaching the server, the Saves tab and the setup screen show a spinner labelled Connecting to RomM…. If the server is briefly slow or flaky, the plugin retries a couple of times before giving up, and the spinner shows which attempt is in progress — Connecting to RomM… (attempt 2/3) — so a slow connection reads as busy rather than stuck. Several parts of the page can be waiting on the server at once, so the count follows the furthest one along and never walks backwards while a page is loading. Once the plugin already knows the server is unreachable it stops retrying — one attempt, then the answer — so the spinner reads plain Connecting to RomM… with no attempt to count, and the offline state arrives quickly instead of after a full round of retries.
You don't need to do anything: while a game page is open, the plugin checks the server roughly every 30 seconds in both directions. If RomM goes away, the RomM offline badge appears on its own within that window; the moment RomM is reachable again the badge clears, Download and slot switching re-enable, and the saves list, achievements, and setup screen reload themselves on the spot — no need to leave and re-open the page.
Only a genuine connection failure marks the plugin offline. If RomM replies that it no longer has the thing being asked about — most often because the game was deleted and re-added on the server, which gives it a brand-new id, or because the RomM database was reset and this device's registration disappeared with it — that is the server answering, so the RomM offline badge stays clear and the surface tells you what's missing instead. If you see such a message while the badge is clear, the fix is on the RomM side (re-sync the library, or re-check the game), not with your network.
A slow answer isn't a failure either. The check a game page runs when it opens can take a while on a busy server or over a remote connection; while it's still outstanding the page simply keeps waiting, and the RomM offline badge appears only once something actually reports the server as unreachable. A page that takes a few seconds to settle is not the same thing as a page that found RomM missing.
When the missing thing is this device's own registration — the RomM database was wiped or restored and the id this device was issued no longer exists — you don't have to do anything. Both when the plugin loads (installing an update counts, since that reloads it) and before every save-sync (before a game launches, after it exits, or a manual sync), the plugin first checks that this device's id still exists on the server; the moment it finds the id is gone it registers this device afresh and carries on under the new id. A new entry shows up in RomM's device list; the old, dead one can be ignored. Play time that was recorded but not yet uploaded — sessions played while RomM was away — is carried over to the new registration, so it still lands on the server under this device rather than being stranded.
The first-time save-slot setup screen is the clearest example. If RomM can't find the save data that setup needs, it pauses with "RomM couldn't find the save data for this setup" rather than the "server is not reachable" message, and the offline badge stays clear. Setup deliberately stops there instead of picking a slot for you: the plugin has no trustworthy view of what's on the server, and choosing a slot on that basis could overwrite real saves on the first sync. Re-check the game in RomM (a server database reset re-registers this device automatically — see above), then tap Retry.
Save file not found¶
Symptom: The game detail page shows save status but no save file is being synced.
Fix: What syncs is not one file type. For each game, the plugin asks the emulator that will launch it which files its save consists of, and syncs only those. Where that answer is something the plugin cannot carry — a card many games share, a save inside the game file, a name built from the game's own identity, or nothing established — save sync does nothing for that game rather than guessing. When save sync does nothing, and why explains each case, and the save sync support matrix shows how each system usually lands.
Also check that the game has saved at all — some games use in-game passwords instead of battery saves, so there is nothing to sync.
Saves being overwritten unexpectedly¶
Symptom: Your save keeps reverting to an older version after syncing.
Fix: Check your conflict resolution mode in Save Sync settings. If set to "Always Download", the server version always overwrites your local save. Switch to "Newest Wins" or "Ask Me" if you play on multiple devices.
Also make sure each person using RomM has their own account — shared accounts cause saves to overwrite each other.
Conflict prompt after a crash or power loss¶
Symptom: After an emulator crash, a full disk, or a power loss mid-save, the next sync shows a conflict prompt instead of uploading — and the local save shown is 0 bytes or much smaller than expected.
Why: A crash can leave a 0-byte or truncated save file on disk. The plugin refuses to upload it over your good server copy, because the server overwrites the existing save in place — there would be no older version left to recover. So instead of silently destroying your progress, it asks you to choose.
Fix: In the conflict prompt, pick Use Server to restore the good copy from RomM (the bad local file is moved
aside into the .romm-backup folder next to your saves first, so nothing is lost). Only pick Keep Local if you are
certain the small/empty local file is the one you want to keep — that uploads it and replaces the server copy.
If you need to recover a save by hand, look in the .romm-backup folder inside your saves directory (e.g.
<saves_path>/gba/.romm-backup/): every file the plugin moves aside is timestamped there. The plugin moves a save aside
whenever it is about to be overwritten or removed — not just when resolving a conflict with Use Server, but also
when you switch save slots and when the setup wizard copies an archived save (one uploaded without a slot) into a slot.
Backups are not kept forever. The folder keeps the newest 10 backups per save file; older ones are pruned the
next time that same save is moved aside. Backups of a different save file are never pruned to make room. If you want to
keep a particular recovery copy long-term, move it out of .romm-backup yourself.
Artwork Missing¶
No SteamGridDB API key¶
Symptom: Games have cover art but no hero banner, logo, or wide grid image. The detail page background is blank.
Fix: Configure a SteamGridDB API key in Settings › Connections. It's free — create an account at steamgriddb.com and copy your API key.
Game not found on SteamGridDB¶
Symptom: Some games have full artwork while others are missing hero/logo/wide grid even with an API key configured.
Explanation: Automatic matching links your ROM to a SteamGridDB game via its IGDB id, and that cross-reference is sometimes missing — especially for obscure ports and regional releases — even when SteamGridDB does have artwork under a differently-linked entry.
Fix: The durable fix is on your RomM server — set the correct SteamGridDB id on the game (or enable the SteamGridDB metadata source and rescan). RomM is the source of truth for artwork matching, so the plugin picks up the corrected id on the next sync or Refresh Artwork. When RomM and the IGDB cross-reference both come up empty, Refresh Artwork opens a picker where you can search SteamGridDB by name and apply a match on the spot — but that pick is temporary and is replaced once RomM provides an id for the game. If a game genuinely has no artwork uploaded to SteamGridDB, those slots fall back to Steam's defaults — you can contribute artwork there to help the community.
Artwork not appearing after sync¶
Symptom: After a sync, some library tiles show Steam's default placeholder instead of the cover art.
Explanation: Covers are applied while the sync runs and fill in progressively, but Steam caches a brand-new shortcut's tile image and does not always refresh it right away. A tile that is still gray usually resolves on its own the first time you open that game's detail page, scroll it back into view, or the next time Steam restarts — the cover is already on disk; Steam just hasn't re-rendered the tile yet.
Fix: If a tile stays blank after that, open the game's detail page and tap Refresh Metadata in the Tender panel. This re-fetches all artwork and metadata. (Hero banners, logos, and wide grid images additionally need a SteamGridDB API key — see above.)
Shortcuts Appear on Other Devices¶
Symptom: Games synced on your Steam Deck also appear on your HTPC (or vice versa), but without artwork. They disappear when the source device goes offline.
Explanation: This is Steam's Remote Play discovery protocol, not a plugin bug. Steam automatically advertises all non-Steam shortcuts to other Steam clients on the same network. These "phantom" shortcuts are ephemeral — they only exist while both devices are online.
The plugin cannot prevent this. Your options are:
- Disable Remote Play entirely in Steam Settings > Remote Play
- Ignore them — they show a "Stream" button instead of "Play" so they're distinguishable
For technical details, see Steam Remote Play and Cross-Device Shortcuts.
Downloads Stuck or Failed¶
Download shows no progress¶
Fix: Check your connection to the RomM server (the Connection row on the plugin's main QAM panel). If the server is reachable, try cancelling and restarting the download from the game detail page.
Download failed¶
Fix: Open the Downloads page from the QAM to see error details. Common causes include insufficient disk space, network interruption, or the ROM being unavailable on the server. Failed downloads can be retried from the game detail page.
Data Management¶
The Data Management page is an inventory of what this device holds. Each row on the left names a population — a set of things that is on your device — and carries its count; picking a row shows what that population is, the numbers about it, and whatever can be done with it. Most rows offer one action, Other non-Steam games offers a removal and a whitelist, and Recovery bundles offers none at all. The six rows are Tender's shortcuts, Installed ROMs, Grid images, Other non-Steam games, Gone from RomM and Recovery bundles.
A count shows a small spinner while it is being read, and a dash if it could not be read. Two counts cost a server round trip or a backend scan, so they read scan until you press for them: Grid images and Gone from RomM; while that scan runs, its row shows the spinner and the button says it is scanning. When a count could not be read, its pane says so and how to try again: open the page again for most rows, or press the scan button again for a scan that failed. Grid images keeps what its scan found until a removal changes it (see Grid images); Gone from RomM keeps it until a cleanup run finishes — which is what changes the number — and then asks to be scanned again. Every destructive action asks first — press once to see the prompt, press again to confirm. The per-platform actions — removing one platform's shortcuts, deleting its save files, deleting its BIOS files — live in Library › Platforms, on the platform's own pane.
While a library sync is running (or cancelling), the shortcut and ROM removals and the grid-image cleanup are unavailable — the buttons are disabled with a short hint, and the backend refuses the request too. Wait for the sync to finish or cancel it first. Save-file and BIOS deletions are not affected.
Gone from RomM¶
This is the only workflow that deletes retained local database rows for games RomM no longer has. The initial scan may show a candidate, but deletion still requires a fresh exact-id 404 during the confirmed run and another check after long recovery or Steam work. A skip is therefore expected if RomM comes back, the response is uncertain, a download starts, local state changes, recovery cannot seal, or Steam cannot confirm its action.
While cleanup is starting or running, library sync, downloads/resumes, migrations, version switches, save mutations, session finalization, launch evaluation, core/disc changes, Steam Input application, uninstalls, and relevant cache cleanup are refused. Frontend Steam continuations hold bounded expiring leases until acknowledged, so a lost page or bridge response cannot block cleanup forever. Active work renews its lease while applying Steam changes; a lease expires only after five minutes without a successful renewal. Component/plugin teardown stops future Steam writes and renewal, but a lease is not explicitly released while an already-started Steam operation is still settling. An unresolved continuation stops renewing after its bounded frontend lifetime and then relies on backend expiry. Server, sign-in, token, and user changes (including a connection test that can backfill user identity) are refused during the run, and every exact-id check also verifies the same server/user namespace captured by the preview. Cancel or finish the cleanup before retrying those actions. This reciprocal block prevents newly downloaded content or recovered state from appearing after recovery was captured and then being removed by finalization.
Recovery bundles are under ~/romm-tender-recovery/bundles/. Older bundles sealed under
~/decky-romm-sync-recovery/bundles/ stay where they are — nothing moves them, and both folders are yours to keep or
delete. A directory appears there only after every required copy and checksum succeeds, directory durability succeeds
where supported, and the staging directory is atomically sealed. A post-rename durability failure preserves the
directory with a .durability-uncertain suffix instead of making it look successfully sealed. Before the Steam action
and again before local finalization, the backend verifies the seal, manifest/checksums, bundle-bound source claims,
source root/descendant identities, mount IDs and bytes, expected absence of currently missing saves, database state,
save ownership, and captured Steam/controller state. Filesystem mutation then holds kernel writer-exclusion leases
through descriptor-relative removal; replacing a path, keeping a writable file descriptor open, crossing a nested mount,
or creating a previously absent save after sealing does not authorize deletion. Save quarantine publishes with atomic
no-replace semantics, so a backup created concurrently is preserved rather than overwritten. Recovery destination
directories and files stay attached to held descriptors through metadata updates, hashing, sealing, and validation, so a
swapped symlink is not re-authorized. A failed attempt may report recovery_failed; it leaves the local game unchanged.
Incomplete staging is removed only when descriptor-relative, mount-aware cleanup proves the tree safe. Otherwise the
error names the full path of that preserved staging so mounted or uncertain data is never traversed recursively.
Free-space blocking in the modal covers the installed ROM content you selected. The backend checks actual source size
and free space again at copy time, so a later disk-space change can still stop the group safely.
The cleanup report is per group: unrelated groups continue after a skip or failure. Large runs deliver terminal details in serialized-byte-bounded chunks, which the UI assembles only after every earlier chunk arrives. A partial result means the report lists a Steam or filesystem action that committed or became ambiguous before a later guard failed; read that group's concrete message and save warnings before retrying. If a recovery bundle was sealed but a later liveness or Steam check aborted, keep the bundle; it is a valid pre-action snapshot even though no local row was deleted. Recovery has no automatic import flow.
A bulk shortcut removal is paced so it never freezes the interface, so on a large library it can take a few seconds. While one is running, every removal button on every pane is disabled and a spinner above the list names the operation and counts off the shortcuts it has removed; the buttons re-enable and the final count appears once it finishes. You can't start a second removal (or a new one from another button) until the current one completes.
Tender's shortcuts¶
The row counts the shortcuts this plugin created. Remove all shortcuts removes every one of them, across all platforms; collections are cleaned up with them. It also sweeps up any shortcut of ours that Steam still holds without a record on our side — what a run interrupted mid-apply leaves behind — so the button stays useful when the count reads zero. Downloaded ROM files and save files are left where they are, and the next sync puts the shortcuts back.
Installed ROMs¶
The row counts the installs this plugin downloaded — one per install, so a multi-disc game counts once and two installed
versions of one game count twice — and the pane states their total size with a ≈. That size is what your RomM server
reported for those games rather than a measurement of your disk, so it is close rather than exact — an unpacked archive,
a patch beside the original or extras in the same folder are not what the server named, and a game whose size the server
never reported adds nothing to it.
Uninstall all ROM files deletes them from disk. Shortcuts remain in your library so you can download the games again. Use this to reclaim disk space.
Grid images¶
Deletes leftover Steam grid images (the grid/ cover, hero, logo, icon and wide files) whose shortcut no longer exists.
Removing or re-creating shortcuts leaves these image files behind, and they accumulate over time.
An image counts as orphaned only when all of these hold:
- its filename is a Steam grid-image name for a non-Steam shortcut appId — custom images you saved for regular Steam games are never touched,
- that appId belongs to no live shortcut — the plugin scans your full shortcut list first, so images of shortcuts from other tools (Heroic, Lutris, manually added games, …) are protected too, not just RomM's.
The row reads scan until you press Scan for orphaned images, which counts them without deleting anything and puts the number on the row. The button then offers to remove that many, and asks once before it does. Deletion is permanent — there is no backup. If the shortcut scan can't run, or any synced RomM shortcut is missing from it, the cleanup refuses and deletes nothing, and the row keeps its count.
The removal looks for orphaned images again when it runs, so it also takes any left behind since the scan. While it runs, the page is busy and no other removal can start. Afterwards the row reads 0 only when every image the removal found was deleted. If some could not be deleted, the pane says how many, and the row goes back to scan; the same happens when the removal's result never came back. Removing Tender's shortcuts or other non-Steam games, or finishing a Gone from RomM cleanup, also puts the row back to scan, because each can leave images the scan did not count — a Tender shortcut the plugin had no record of, a non-Steam game whose images nothing here deletes, or a cleanup run without recovery, which leaves its games' images behind. Press Scan for orphaned images again to count what is left.
Other non-Steam games¶
Everything in your Steam library that neither Steam nor this plugin installed — emulators, launchers, browsers, games you added by hand. Your RomM games are not in this row, and the removal here cannot touch them: this plugin's own shortcuts are told apart by what they launch, not by their names, and removing them is the Tender's shortcuts row's job.
If Steam's shortcut list cannot be read, that ownership cannot be established — the count shows a dash, the pane says the list could not be read, and the removal is refused rather than guessed at. Steam also does not always answer for an individual shortcut in time; those entries are counted neither way, are never offered for removal, and the pane says how many it is leaving alone.
A whitelist system lets you protect the rest from removal:
- Press Configure whitelist
- Toggle on any games you want to protect (RetroDECK is auto-protected by default)
- Use the search box to find specific games in long lists
- Protected games are excluded from the removal count
The plugin shows extra warnings if RetroDECK is not whitelisted, since removing it would break all emulation.
Recovery bundles¶
The row counts the snapshots the cleanup sealed under ~/romm-tender-recovery/bundles/, and states the disk they take.
Below that total the pane lists each bundle with the game it holds, the day (UTC) it was sealed as its folder name
carries it, and its size, newest first. The game is spelled the way the bundle's folder spells it — Shenmue-II for
Shenmue II — so it matches what you see in a file manager. A folder whose name is not in the shape Tender writes — one
you renamed, or one ending .durability-uncertain because its seal could not be confirmed — is listed under its folder
name, with no day, at the bottom. Nothing on this page removes one — they are yours to keep, move or delete in a
file manager. What a bundle holds is under Gone from RomM above.
The count covers that folder only. Bundles an older version sealed under ~/decky-romm-sync-recovery/bundles/ are still
on your disk and are not counted here, so a device carrying those has more than this row reports.
Per-platform removals moved¶
Removing one platform's shortcuts, deleting its save files and deleting its BIOS files are on that platform's pane in Library › Platforms, each behind its own confirmation. See Removing a platform from Steam and Deleting BIOS files.
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