function plt_hide_megaoptim_image_optimizer_menus() {
//Hide the "Media → Bulk MegaOptim" menu.
remove_submenu_page('upload.php', 'megaoptim_bulk_optimizer');
//Hide the "Settings → MegaOptim" menu.
remove_submenu_page('options-general.php', 'megaoptim_settings');
}
add_action('admin_menu', 'plt_hide_megaoptim_image_optimizer_menus', 21);