You may have noticed that it is nearly impossible to delete a Facebook account. Some believe it is impossible. However, on the ReadWriteWeb.com blog they have the steps needed to backup your profile and delete it.
There are other ways. As one person has said, just post something politically incorrect and Facebook Staff will delete it for you. Another is to have a friend report you as a fake person, one using an alias. Another is to convince them you’re an avatar.