diff --git a/apps/www/src/client/App.tsx b/apps/www/src/client/App.tsx
index ccafb37..4a92268 100644
--- a/apps/www/src/client/App.tsx
+++ b/apps/www/src/client/App.tsx
@@ -3213,6 +3213,7 @@ function PublicRoomView({
 				<>
 					{isDeveloper() && <StaffRoomTokens room={room} />}
 					<StaffListing room={room} onRoomChange={onRoomChange} />
+					<StaffClearInstances room={room} />
 					{isDeveloper() && <StaffTakedown room={room} onTakenDown={onTakenDown} />}
 				</>
 			)}
@@ -3351,6 +3352,64 @@ function StaffListing({
 	)
 }
 
+/**
+ * Delete every instance of the room, for one whose sessions are stuck. Two steps, like the
+ * dorm clear: nothing is lost for good, but anyone inside is cut off from their session.
+ */
+function StaffClearInstances({ room }: { room: OwnedRoom }) {
+	const [confirming, setConfirming] = useState(false)
+	const { pending, error, done, run } = useAction()
+
+	return (
+		<section className="card">
+			<h2>Instances</h2>
+			<p className="hint">
+				Deletes every instance of this room, including ones with players in them. The next player to
+				join gets a fresh instance.
+			</p>
+			<div className="mod-filter-actions">
+				{confirming ? (
+					<>
+						<button
+							type="submit"
+							disabled={pending}
+							onClick={() =>
+								void run(async () => {
+									const res = await call<{ deleted: number[] }>(
+										`/api/staff/rooms/${room.RoomId}/clear-instances`,
+										{ authed: true, method: 'POST' }
+									)
+									setConfirming(false)
+									const n = res.deleted.length
+									return n === 0
+										? `^${room.Name} had no instances.`
+										: `Cleared ${n} instance${n === 1 ? '' : 's'} of ^${room.Name}.`
+								})
+							}
+						>
+							{pending ? 'Clearing…' : 'Confirm clear instances'}
+						</button>
+						<button
+							type="button"
+							className="linkish"
+							disabled={pending}
+							onClick={() => setConfirming(false)}
+						>
+							Cancel
+						</button>
+					</>
+				) : (
+					<button type="submit" onClick={() => setConfirming(true)}>
+						Clear instances
+					</button>
+				)}
+			</div>
+			{error && <p className="error">{error}</p>}
+			{done && <p className="ok">{done}</p>}
+		</section>
+	)
+}
+
 function StaffTakedown({ room, onTakenDown }: { room: OwnedRoom; onTakenDown: () => void }) {
 	const [confirming, setConfirming] = useState(false)
 	const { pending, error, run } = useAction()
diff --git a/apps/www/src/staff.ts b/apps/www/src/staff.ts
index ede4d9b..e92023d 100644
--- a/apps/www/src/staff.ts
+++ b/apps/www/src/staff.ts
@@ -4,6 +4,7 @@ import {
 	clearDormSaveBlob,
 	clearPasswordHash,
 	createGift,
+	deleteRoomInstancesByRoom,
 	getAccount,
 	getImageById,
 	getOnlinePlayerIds,
@@ -1016,6 +1017,28 @@ export async function giftRoomTokensHandler(c: Context<App>) {
 	return c.json({ roomId, amount, paid, skipped })
 }
 
+/**
+ * Delete every instance of a room from `room_instance`, from the room's own page. For a
+ * room whose sessions have gone bad: the next player to matchmake in gets a fresh one.
+ * Clearing a room with no instances succeeds and deletes nothing.
+ */
+export async function clearRoomInstancesHandler(c: Context<App>) {
+	const roomId = Number(c.req.param('roomId'))
+	if (!Number.isInteger(roomId) || roomId <= 0) {
+		return c.json({ error: 'A numeric room id is required' }, 400)
+	}
+
+	const deleted = await deleteRoomInstancesByRoom(c.env.DB, roomId)
+
+	await recordPlayerAudit(c, 'clear_room_instances', { roomId, deleted })
+	logger.info('staff cleared room instances', {
+		moderatorId: staffId(c),
+		roomId,
+		deletedCount: deleted.length,
+	})
+	return c.json({ roomId, deleted })
+}
+
 /**
  * Send tokens to EVERYONE ONLINE right now — the server-wide drop behind the account page's
  * "Token drop" tab, beside the coach broadcast and the maintenance notice.
diff --git a/apps/www/src/test/integration/api.test.ts b/apps/www/src/test/integration/api.test.ts
index cbdb762..205d2ec 100644
--- a/apps/www/src/test/integration/api.test.ts
+++ b/apps/www/src/test/integration/api.test.ts
@@ -22,7 +22,11 @@ import {
 	setPresence,
 } from '@repo/domain/src/presence-db'
 import { getProgression, PROGRESSION_SCHEMA_DDL } from '@repo/domain/src/progression-db'
-import { ROOM_INSTANCE_SCHEMA_DDL } from '@repo/domain/src/room-instance-db'
+import {
+	createRoomInstance,
+	getRoomInstancesByRoom,
+	ROOM_INSTANCE_SCHEMA_DDL,
+} from '@repo/domain/src/room-instance-db'
 // Banning a player moves them into their own dorm, which is a room (created on demand) with
 // a subroom — so those tables have to be here, as they are on the shared database.
 import { getOrCreateDormRoom, ROOM_SCHEMA_DDL, SUBROOM_SCHEMA_DDL } from '@repo/domain/src/rooms-db'
@@ -1087,6 +1091,7 @@ it('refuses every staff endpoint without a token, and without a staff role', asy
 		'/api/staff/players/1/username-changes',
 		'/api/staff/players/1/clear-password',
 		'/api/staff/players/1/clear-dorm',
+		'/api/staff/rooms/1/clear-instances',
 		'/api/staff/studio-access',
 		'/api/staff/players/1/grant-plus',
 	]
@@ -2472,6 +2477,31 @@ it('clears a player’s dorm by publishing an empty save over the newest one', a
 	])
 })
 
+it('clears every instance of a room, for any staff member', async () => {
+	const make = (roomId: number, photonRoomId: string) =>
+		createRoomInstance(env.DB, { ownerAccountId: 8110, roomId, photonRoomId })
+	const a = await make(7740, 'clear-a')
+	const b = await make(7740, 'clear-b')
+	const other = await make(7741, 'clear-other')
+
+	// A moderator, not only a developer, may clear a room.
+	const res = await staffPost('/api/staff/rooms/7740/clear-instances', 8101, {})
+	expect(res.status).toBe(200)
+	const body = (await res.json()) as { roomId: number; deleted: number[] }
+	expect(body.roomId).toBe(7740)
+	expect(body.deleted.toSorted()).toEqual([a.roomInstanceId, b.roomInstanceId].toSorted())
+	expect(await getRoomInstancesByRoom(env.DB, 7740)).toEqual([])
+	// Another room's instances are untouched.
+	expect((await getRoomInstancesByRoom(env.DB, 7741)).map((i) => i.roomInstanceId)).toEqual([
+		other.roomInstanceId,
+	])
+
+	// Clearing an empty room succeeds and deletes nothing.
+	const again = await staffPost('/api/staff/rooms/7740/clear-instances', 8101, {})
+	expect(await again.json()).toEqual({ roomId: 7740, deleted: [] })
+	expect((await staffPost('/api/staff/rooms/abc/clear-instances', 8101, {})).status).toBe(400)
+})
+
 it('grants a player Plus, developers only', async () => {
 	await updateAccount(env.DB, 8330, { username: 'Plusless' })
 	const hasPlus = async () =>
diff --git a/apps/www/src/www.app.ts b/apps/www/src/www.app.ts
index 2024a71..c21aaab 100644
--- a/apps/www/src/www.app.ts
+++ b/apps/www/src/www.app.ts
@@ -51,6 +51,7 @@ import {
 	bansInForceHandler,
 	clearDormHandler,
 	clearPasswordHandler,
+	clearRoomInstancesHandler,
 	createReportHandler,
 	getReportHandler,
 	giftItemHandler,
@@ -813,6 +814,8 @@ const app = new Hono<App>()
 	.post('/api/staff/players/:id/gift-xp', requireDeveloper, giftXpHandler)
 	// Everyone standing in a room, across all of its instances.
 	.post('/api/staff/rooms/:roomId/gift-tokens', requireDeveloper, giftRoomTokensHandler)
+	// Delete every live instance of a room — for one whose sessions are stuck. All staff.
+	.post('/api/staff/rooms/:roomId/clear-instances', clearRoomInstancesHandler)
 	// The account page's token drop: the same gift to everyone online at once.
 	.post('/api/staff/online/gift-tokens', requireDeveloper, giftOnlineTokensHandler)
 	// Its sibling: the same gift to every account whose Discord link holds a role, offline
diff --git a/packages/domain/src/room-instance-db.ts b/packages/domain/src/room-instance-db.ts
index 325846d..4332d2d 100644
--- a/packages/domain/src/room-instance-db.ts
+++ b/packages/domain/src/room-instance-db.ts
@@ -476,6 +476,25 @@ export async function deleteEmptyRoomInstances(
 	return results.map((r) => r.id)
 }
 
+/**
+ * Delete EVERY instance of a room, occupied or not — the staff "Clear instances" button
+ * for a room whose sessions are stuck. Presence is left alone: a player still in a
+ * deleted instance keeps their row until it expires or they move, and their next
+ * matchmake lands them in a fresh instance.
+ *
+ * Returns the ids deleted.
+ */
+export async function deleteRoomInstancesByRoom(db: D1Database, roomId: number): Promise<number[]> {
+	const { results } = await db
+		.prepare(
+			`DELETE FROM room_instance WHERE room_id = ?1
+			 RETURNING json_extract(data, '$.roomInstanceId') AS id`
+		)
+		.bind(roomId)
+		.all<{ id: number }>()
+	return results.map((r) => r.id)
+}
+
 /**
  * The oldest joinable public instance of a room (not private, not full, joins
  * enabled, not already in progress, not set to `Ignore`) that is running `gameVersion`,