To cancel your account, log in and click on the Account tab. This will send you to Account Default Page. Scroll down the page to the Section "Selling Account Options" select the "Close Account" link.
If you have a Premium Payloadz subscription that was created via PayPal, you will get an alert that you need to cancel your PayPal subscription with Payloadz.com first and you will be linked directly to PayPal's search to complete that process. The system will not let you close the account until you downgrade as your account will continue to be billed if you don't cancel through PayPal.