Hi, welcome to the Community! 
I moved your post - it’s better to start your own thread… please see more guidelines here:
I just removed this by commenting-out this section in include/globalControlLinks.php, and it worked:
$global_control_links['training'] = array(
'linkinfo' => array($app_strings['LBL_TRAINING'] =>
'javascript:void(window.open(\'https://suitecrm.com/suitecrm/forum/suite-forum\'))'),
'submenu' => ''
);
Are you sure you’re doing this right?
Warning: done like this, the change won’t be upgrade-safe. The correct way to do it is to leverage this mechanism here:
You could add a custom file (your PHP will run after these definitions are made) undefining the $global_control_links['training'] array entry.