clear cache on MacBook Air

If these are showing up as notifications, start here:

Stop unwanted Notifications - Apple Community

If they are showing up as browser pop-ups, see this:

Block pop-up ads and windows in Safari - Apple Support

domibear64 wrote:

I never installed it

When and where are these notifications appearing?

If these notifications are popping up in your browser then disable browser notifications.

domibear64 wrote:

I keep on getting a popup from Norton Virus

Uninstall Norton.