Removing a link below from footer

The part you need to remove is this: add_action( 'wp_footer', 'addcopy' );. Or remove it with remove_action, like so:

remove_action('wp_footer','addcopy');

However, if your theme has included this link in such a way that you cannot easily remove it– that is, cannot remove it with a theme option without hacking the code– then there is probably something in the Terms of Use saying you can’t remove it.

Get a different theme. In addition to violating the terms, I don’t trust themes (or plugins) that force link-backs on the front end. You don’t know what else they might be hiding.