Here are the simple steps needed for cancellation request:

Login with your billing account at http://billing.vpsfx.com. If you can't remember your password, you can request a password reset from this page you don't remember your password, click here.  After you logged in click on "Services"->"My services" menu link at the top of the page and you'll see the list of your VPS services. Click the "view details" button at the right of the VPS you want to cancel. Briefly describe your reason for cancellation and click on the "Request Cancellation" button