-or by telephone http://helpx.adobe.com/x-productkb/global/phone-support-orders.html
This is an open forum, not Adobe support... you need Adobe support
Adobe contact information - http://helpx.adobe.com/contact.html may help
-Select your product and what you need help with
-Click on the blue box "Still need help? Contact us"
Quick question because this may change what is going to happen when you cancel. How long have you had Adobe CC?