I should have trusted the negative reviews on American Home Shield or AHS that I read before and NEVER have used them. They have all the markings of a scam operation. They let you do everything online EXCEPT for cancelling coverage. They drag their feet forever on the cancellation process. When you talk to someone on the phone, they claim they are not setup to send emails. This way you don't get any confirmation from them and mailed correspondence gets "lost".
My advice: if you want to cancel, just file a dispute with your credit card company so they can't charge you any more.