How to Hide the "PWA+PHP" Admin Menu

function plt_hide_pwaplusphp_menus() {
	//Hide the "Settings → PWA+PHP" menu.
	remove_submenu_page('options-general.php', 'pwaplusphp');
}

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

Where do I put this code?