Here's the link i had saved when i joined FB in 2007; to permanently delete a facebook A/c, also included are the following steps:

1. Login facebook

2. Copy & Paste this link in you browser & hit enter: 
    https://ssl.facebook.com/help/contact.php?show_form=delete_account

3. Confirm deactivation & your facebook A/c will be permanently deactivated in 15 days.
=>Cheers ;)