How to Hide MondoPlayer Admin Menus

function plt_hide_mondoplayer_menus() {
	//Hide "MondoPlayer".
	remove_menu_page('mondoplayer_menu_slug');
	//Hide "MondoPlayer → Search".
	remove_submenu_page('mondoplayer_menu_slug', 'mondoplayer_menu_slug');
	//Hide "MondoPlayer → Categories".
	remove_submenu_page('mondoplayer_menu_slug', 'mondoplayer_menu_categories_slug');
	//Hide "MondoPlayer → AutoPilot".
	remove_submenu_page('mondoplayer_menu_slug', 'mondoplayer_menu_autopilot_slug');
	//Hide "MondoPlayer → Posts".
	remove_submenu_page('mondoplayer_menu_slug', 'mondoplayer_menu_posts_slug');
	//Hide "MondoPlayer → Settings".
	remove_submenu_page('mondoplayer_menu_slug', 'mondoplayer_menu_settings_slug');
	//Hide "MondoPlayer → Notifications".
	remove_submenu_page('mondoplayer_menu_slug', 'mondoplayer_menu_notifications_slug');
}

add_action('admin_menu', 'plt_hide_mondoplayer_menus', 21);

Where do I put this code?