How to Hide Photo Gallery by Supsystic Admin Menus

function plt_hide_gallery_by_supsystic_menus() {
	//Hide "Photo Gallery by Supsystic".
	remove_menu_page('supsystic-gallery');
	//Hide "Photo Gallery by Supsystic → Photo Gallery by Supsystic".
	remove_submenu_page('supsystic-gallery', 'supsystic-gallery');
	//Hide "Photo Gallery by Supsystic → Overview".
	remove_submenu_page('supsystic-gallery', 'supsystic-gallery&module=overview');
	//Hide "Photo Gallery by Supsystic → New gallery".
	remove_submenu_page('supsystic-gallery', 'supsystic-gallery&module=galleries&action=showPresets');
	//Hide "Photo Gallery by Supsystic → Image Optimize".
	remove_submenu_page('supsystic-gallery', 'supsystic-gallery&module=optimization');
	//Hide "Photo Gallery by Supsystic → Galleries".
	remove_submenu_page('supsystic-gallery', 'supsystic-gallery&module=galleries');
	//Hide "Photo Gallery by Supsystic → Settings".
	remove_submenu_page('supsystic-gallery', 'supsystic-gallery&module=settings');
}

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

Where do I put this code?