If they ban you your posts don't get deleted,so if that's what you're going for you're going to need to cough up the money to be a donor and then go delete your own posts. Otherwise, why do you need to be banned? How is that different from just ignoring the account? If it's a self control thing change your password to something uber random and long and then don't write it down. When you forget your password you won't be able to get into the account any more.