Completely remove ability to create users?

Question

I have added the code below to a plugin:

add_action( 'admin_init', 'remove_add_users_cap' );
function remove_add_users_cap() {
    $role = get_role( 'administrator' );
    $role->remove_cap( 'add_users' );
    $role->remove_cap( 'create_users' );
}

And I can see that the caps are no longer on my user:

if(!function_exists('wp_get_current_user')) {
    include(ABSPATH . "wp-includes/pluggable.php"); 
}
$current_user = wp_get_current_user();
echo '<pre>';
print_r($current_user);
echo '</pre>';

But I can still add new users O.o ...

Is there something else that needs to be done to achieve this? I would like to completely remove the ability for anyone to add a new user when this plugin is activated...

This is in a Wordpress Multisite context, and I have a feeling that may be complicating things.

Thanks,

Answer 1

Okay, so the code above does work, but not for super admins, you must explicitly remove permissions from super admins, like this:

// restrict super admin capabilites
add_filter('map_meta_cap', 'restrict_super_admins', 10, 4);
function restrict_super_admins($caps, $cap, $user_id, $args){
    $super = array(
        'add_users',
        'create_users',
    );
    if( in_array($cap, $super) ) {
        $caps[] = 'do_not_allow';
    }
    return $caps;
}