You should be able to reset your account to negate all your keys and set things back up if you lost access to all previous devices.
I ended up doing this anyway in the end, after deleting everything I could before I stopped using it.
They do make you wait seven days before you can do it after you make the request.
I still have the account because I don't want to lose access to my username (didn't delete it), but it's otherwise empty and unused with fresh keys that have no history with anything.
Granted, I haven't used it in a while because they put me in a position where recovering my account is impossible.