To cancel your current service, please follow the below steps:
1) Login to your account at http://www.hiperz.com
2) Click on "My services", you will see the list of all services
3) Next to the Product/Service you wish to cancel click on the "View Details" button
4) Click on the Management Actions tab and then click on "Request Cancellation"
Note: If you have an active PayPal subscriptions you will have to cancel it from the paypal website.
In any case ignoring a renewal invoice will result into the servive being cancelled automatically along with all the data in it.