В июле 2019 получилось отменить подписку так:

Hello! I have Acrobat Pro DC annual plan an I'd like to cancel it. Could you please cancel it?
Adobe Customer Care Assistant

Ok. I want to make sure I understand clearly. Which category below best describes your issue?
Cancel a plan

Pratiksha

Hello, I'll be happy to assist you. I understand you want to cancel your plan, may I know reason of cancellation?
I have an old x86 Windows XP system, and Acrobat Pro DC doesn't support it
Pratiksha

If you wish to continue using the subscription then I can add 3 free months to it, this means you will not be charged for next 3 months and you can use the subscription for free for 3 months, how does that sound?
no thanks. I can't use it because my hardware is too old.
Pratiksha

Okay I will go ahead and cancel your plan.
Sorry to see you go. While I process your cancellation, I want to let you know that you still have access to several free Adobe products, such as Adobe Spark or XD. I hope you'll use Adobe products again in the future.
Thank you very much for help
Pratiksha

Your plan has been cancelled you will receive an email confirming the same.
I hope that helped. You'll receive an email with a survey link. Please take a moment to rate your experience and help us improve. Thanks!