As per your account description it seems that you have already managed to get your subscription canceled.
In future if you experience the same problem or screen goes blank you may check with a different web browser.
For the exact steps, you may refer to the- Manage your Creative Cloud membership
Also, for any further assistance you may contact to the- Contact Customer Care
Hope this helps.
Thanks for the advice Akanchha. Eventually, I talked to Adobe and they cancelled the subscription manually.