Login to the client area at https://www.fast2host.com/clientarea.php
Select "My Products & Services"
For the product you want to cancel, select "View Details"
At the bottom is a "Request Cancellation" button, select this.
Please give a brief description of the reason for Cancellation, select "Immediate" or "End of billing period", and then submit the request.
If you are due a refund for unused time on your account, this will be refunded back to your card.