Only admins can delete accounts though that is not done. The only accounts deleted are those of spam bots. All other accounts are not deleted as it easily corrupts the data base/forum as everything associated with that account is deleted as well from vms to pms, reputation comments, posts, threads, IP reccords for Alternate Account matching, etc etc. If you don't want to log in anymore and can't trust yourself to do so, simply change your email to something random, change your password to something even more random and log out.