How can I get rid of the hundreds of pop up windows from McAfee??

In addition go to Safari > Settings > Websites > Popup Windows. Remove all, unless known site you allow a pop up.

Go to Safari > Settings > Extensions. Turn all off or remove.

If you have McAfee installed and want to know how to remove, please advise further.

You're being bludgeoned by notifications. Nothing at all to do with popups or extensions.

Safari > Preferences/Settings > Websites

Scroll down in the left column to Notifications. Remove any entries at the right.

Go to Safari > Settings > Websites > Notifications. Remove all.