This is probably the saddest question for us to answer. Therefore, before you make that decision, we would like to kindly ask you to think twice 😀
Anyway, you can cancel your Stack subscription at any time. And of course, you will maintain all Pro features till the next billing date.
For canceling the subscription, simply Go to:
Profile >> Memberships >> Danger Zone
The gif below illustrates it as well:

P.s. The information given above may be irrelevant or outdated. We will be updating the page soon. Sorry for the inconvenience and thank you for your patience!