Stop renewal alerts

How do I fully remove Norton from my computer? I no longer use Norton's service but am plagued by their prompts to renew their service. Currently, every time I turn on my computer I have to go thru a series of opting out on product renewals before I can do anything else and I am, quite franklly, tired of the hassle. I no longer use their service, I do not want to use Norton now or in the future but can't figure out how to completely purge them from my system. Help!