Add tags to custom post type without menu link

To remove the submenu Tags link from the admin menu, you might try

add_action( 'admin_menu', 'custom_admin_menu' );
function custom_admin_menu() {
        // debug to find the correct submenu slug:
        // global $submenu;
        // print_r($submenu);

        $menu_slug = 'edit.php?post_type=infographics';
        $submenu_slug = 'edit-tags.php?taxonomy=post_tag&post_type=infographics';

        remove_submenu_page( $menu_slug, $submenu_slug );
}

if your custom post type is infograhpics.

By viewing the global $submenu array you can find the correct menu slugs.