Stop unwanted Notifications
Are you encountering popup notices in the upper right of your Mac's screen, resembling the following typical examples?
Hopefully you already know they are scams. The familar-looking icons and text are utterly meaningless lies. Clicking them will cause another website to load, which will subsequently attempt to deceive or frighten you into downloading and installing something you do not need. That's the real threat.
Stop them by following these instructions.
- Go to Safari's Preferences (or Settings) menu > Websites > Notifications, and remove everything there. See the illustration below.
When you are finished, it should look like this:
Do not download or install anything in an effort to get rid of them. Website notifications are not viruses and they are not malware. They are an integral part of the worldwide web standard... for better or worse.
For reference: Change Websites settings in Safari on Mac - Apple Support
So how did this happen
The reason for their appearance is that you granted permission for one or more websites to send notifications, such as in the following example:
They are usually preceded by a solicitation resembling the following:
Needless to say if you do not want to be harassed by such nonsense your automatic response should be to decline. Click Dismiss, Don't Allow, Cancel, Go Away, etc. There is no way for you to control what website owners intend to do with those Notifications after you agree to them, but they almost always have one singular goal in mind: 💰
Do not allow websites to send you Notifications unless you are 100% certain that you want that kind of harassment. Refer to Customize website notifications in Safari on Mac - Apple Support. Deselecting "Allow websites to ask for permission to send notifications" will prevent those websites from even asking your permission to be harassed by them.
Related reference material follows.
Effective defenses against malware and other threats - Apple Community
Phony "tech support" / "ransomware" popups and web pages - Apple Community