No cancellation notice is required. As soon as you are no longer using an outdated PHP version (as of March 2025, PHP 8.1 and above), the PHP Extended Support will be canceled at midnight. There will be no refund for any remaining booked days. We will, of course, confirm the deactivation of PHP Extended Support by email.
You can find instructions on how to change the PHP version under How can I change the PHP version in CloudPit?