I think it is a scam. I've had my phone over a year. I dont have Norton, I to have been bombarded with renew requests. more than 5 a day for last 4 or 5 days. I mark them all as spam
If you had a Norton trial that has expired you will get notification to renew. If its on the mobile uninstall it. If by some reason its on your computer and you have added your phone to your account then go to manage devices and remove mobile.