How to Hide the "w3myPQ" Admin Menu

function plt_hide_w3mypq_menus() {
	//Hide the "Settings → w3myPQ" menu.
	remove_submenu_page('options-general.php', 'w3mypq-settings');
}

add_action('admin_menu', 'plt_hide_w3mypq_menus', 11);

Where do I put this code?