Is it possible to permanently delete a Facebook account in one day? Currently I can delete it only after 14 days.
No, it is not possible. The delay is by design and the reason is one might have second thoughts. It also takes time to scrub everything off, as some tasks might be put on a scheduled queue.
After you request to have your account permanently deleted, we delay the deletion process a few days in case you change your mind. If you log into your account again during this time you'll cancel your deletion request.