Justoverclock Alright so you will need to login to the MySQL server either via phpmyadmin or SSH
Once logged into the database you'll want to run:
USE yourdatabasenamehere;
This tells MySQL which database we are going to run our commands against. The next command will clear your footer completely, I will also be including the command to clear the header since I don't know where you put that CSS/JS HTML code.
DELETE FROM settings WHERE `key` = 'custom_footer';
DELETE FROM settings WHERE `key` = 'custom_header';