How do you disable the manual page? I've changed the line in settings, bb_functions and index.php whereever it says manual and tried commenting those lines out but it still works?

Do not destroy the core scripts just of that simple code... you need to put in bb_plugins.php (any place, preferrably at the very top):

if($action=='manual') { header("Location: https://www.minibb.com/forums/"); exit; }