From Facebook account settings option you can just deactivate your account you can not permanently delete your account. By this way your account information will be there on Facebook, and you can reactivate your account by just loging again.
But if you want to delete your account permanently than visit the given link ...
http://www.facebook.com/help/contact.php?show_form=delete_account
It's a link of Facebook page from where you can delete your account permanently.
