How to Hide WhatsApp Chat Admin Menus

function plt_hide_wp_whatsapp_chat_menus() {
	//Hide "WhatsApp Chat".
	remove_menu_page('qlwapp');
	//Hide "WhatsApp Chat → Welcome".
	remove_submenu_page('qlwapp', 'qlwapp');
	//Hide "WhatsApp Chat → Button".
	remove_submenu_page('qlwapp', 'qlwapp_button');
	//Hide "WhatsApp Chat → Box".
	remove_submenu_page('qlwapp', 'qlwapp_box');
	//Hide "WhatsApp Chat → Display".
	remove_submenu_page('qlwapp', 'qlwapp_display');
	//Hide "WhatsApp Chat → Colors".
	remove_submenu_page('qlwapp', 'qlwapp_colors');
	//Hide "WhatsApp Chat → Premium".
	remove_submenu_page('qlwapp', 'qlwapp_premium');
}

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

Where do I put this code?