this is a problem for nostr in certain kinds of processes too, there is an active issue on the nips repo right now for locking a key... but you really can't lock, first of all, many relays don't even delete, as if they are going to do anything about keys that have been canceled

shoot in the heat of the moment but otherwise if you are sure make sure that they are locked away for multiple "life sentences" (life=25y btw, standard penalty for murder in most countries, even bulgaria)