To cancel: go to https://account.adobe.com/plans and check what plans are there. Plans are not listed as products. Click “manage plan” and cancel. You may have to wait for 24h before you can cancel, however.
If that does not work, contact Adobe support. Adobe customer care can be contacted by beginning a secure chat session at https://helpx.adobe.com/contact.html?rghtup=autoOpen. Pop-up blockers need to be disabled! If the chat window fails to open, or is non-responsive, use a different device to start the interaction.
Support phone numbers may be found here: https://helpx.adobe.com/contact/phone.html. Please note that phone charges may apply.
For support via Twitter:
(see also here: https://community.adobe.com/t5/creative-cloud-services/how-to-contact-adobe-support/td-p/11875703 or here
and beware of private messages from scammers impersonating adobe. follow the one of the 3 ways to contact adobe yourself.