Log on to your Blockbuster Online account with the username and password that you provided when you subscribed to the service.
Select the "My Account" link on the top navigation bar on your screen.
Click on the "Cancel My Account" option on the options menu.
Select "no" on the screen that appears asking if you would reconsider your request to cancel your subscription or change to a different plan.
Complete the survey screen that requests information about your reasons for cancelling the subscription.
Return any DVDs or games that you are renting from the Blockbuster Online service before your next billing cycle.