Delete data kept from a removed account
If you removed a messaging or chat account and checked Keep this account's data on this device, its messages, contacts, and media stay on your device. You can erase them later.
This menu item appears only when a removed account has data on your device. 2. Under REMOVED ACCOUNTS, swipe the account and tap Delete. 3. Tap Done.
If you add the same account again, it no longer appears in this list, because its data is back in use.
See Also Use the Accounts application to edit or delete an online account
Checked against the LuneOS code and installed apps. Nobody has tried these steps by hand yet, so tell us if something differs.