How to Hide Chat Help Admin Menus

function plt_hide_chat_help_menus() {
	//Hide the "WhatsApp Chat" menu.
	remove_menu_page('chat-help');
	//Hide the "WhatsApp Chat → WhatsApp Chat" menu.
	remove_submenu_page('chat-help', 'chat-help');
	//Hide the "WhatsApp Chat → 👑 Upgrade to Pro!" menu.
	remove_submenu_page('chat-help', 'https://themeatelier.net/downloads/whatsapp-chat-help');
}

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

Where do I put this code?