Actually I'm pretty sure you need to call to cancel. I need to cancel tomorrow and logged in to see if I could online and I saw this..
How do I cancel my Trial Membership?
You may cancel your 30-day free trial at any time on or before your expiration date. In order to protect your account, we require that you call us at 1-866-683-5673 and speak to a customer service representative in person and obtain a cancellation confirmation number. Email, voice mail, live chat, and regular postal mail are not acceptable as a method of cancellation. Our Customer Care department is open to assist you with billing and cancellation enquiries from 8AM to 5PM Mountain Time, Monday through Friday