In order to cancel your Norton auto renewal service, you have to log into your Norton Account (https://my.norton.com/). In the main menu, under Your Name link, click on Automatic Renewal Settings link. You’ll see your active subscription, and an option to turn the Automatic Renewal ON or OFF, as on the screenshots below.
We also have a video that shows how to manage auto renewal:
Finally, here are the screenshots of the switch in both ON and OFF mode: