Seems you can't choose to delete an account in the Preferences options...Either that or I'm completely blind. :/ I would suggest you ask the administrator peppy about deleting an account but I'm unsure of if he'll be annoyed by it or not...So safest bet is to wait until the admin comes here and posts something about it or another surefire answer comes.
Besides, you don't
need to delete your account; you can just leave it for dead. (Unless it's another account...but I can't really understand which account you're wishing to delete)