Adobe making it impossible to cancel the plan. Every time I click cancel, it logs me out

No, not despicable.  The online account works for me. Maybe your payment card is not current. Or try another browser/web device that accepts cookies and does not have script blockers or VPN enabled. 😉

Failing that, reach out to Adobe support.

CONTACT ADOBE SUPPORT:
================
Online Chat: https://helpx.adobe.com/contact.html?rghtup=autoOpen
Twitter: https://twitter.com/adobecare
Phone M-F, during normal business hours: https://helpx.adobe.com/contact/phone.html

Hope that helps.

contact adobe support.  there are 3 ways to contact adobe; chat, phone and twitter:

chat:
use a browser that allows popups and cookies, and click here, https://helpx.adobe.com/contact.html?rghtup=autoOpen
in the chat field (lower right), type AGENT
be patient, it can take quite a while to reach a human.

phone:
https://helpx.adobe.com/contact/phone.html

twitter:
tweet @AdobeCare

p.s. if you're contacted by anyone (via email or private message), it's much more likely to be a scammer than an adobe representative. ie, double check for an employee badge if contacted in the forums and look for an adobe.com domain in the email address if you click reply to an email. then check again and be very suspicious. any other method of contacting (or offering to contact you) is almost certainly a scam, https://community.adobe.com/t5/using-the-community-discussions/staying-safe-in-the-adobe-support-community/td-p/12919684/redirect_from_archived_page/true