How to Hide MetaSlider Gallery Admin Menus

function plt_hide_ml_slider_lightbox_menus() {
	//Hide "Gallery".
	remove_menu_page('metaslider-lightbox');
	//Hide "Gallery → Galleries".
	remove_submenu_page('metaslider-lightbox', 'edit.php?post_type=ml_gallery');
	//Hide "Gallery → Settings".
	remove_submenu_page('metaslider-lightbox', 'metaslider-lightbox');
	//Hide "Gallery → Edit Gallery".
	remove_submenu_page('metaslider-lightbox', 'ml-gallery-editor');
}

add_action('admin_menu', 'plt_hide_ml_slider_lightbox_menus', 11);

Where do I put this code?