You can do this by logging into your Online Account Manager at:
http://www.hostingcheck.com/billing/
Then, Click "Services" from the Menu,
Then, Click "My Services" from the Drop Down Menu,
Then, Click on the "Manage" Button next to the Web Hosting Account Domain Name that you want to Cancel.
Then, Click on the "Management Actions" Tab, and choose "Request Cancellation".
Follow the instructions there.
