if you do not have Norton, or if you do and they say the online request is bogus follow the real Norton instructions or delete they phony one. If you see one like that (Norton or any other brand) in a pop up, close it without responding and run your own security software scan to see if they infected you, There are probably better ways to deal with scammers but they are experts and it is best to just not bite on their bait or let your real security folks deal with it. If not infected, I would be sure I had deleted the fake, then shut down or do a restart anyway.