"your iCloud is being hacked" notifications on MacBook Air. How do I get rid of this?

If they are appearing in the upper right hand corner of your screen they are probably coming from some website that you gave permissions to for notifications. In the event that is the case do the following in Safari's Websites settings pane:

k4rizz4:

First, there is no reason to ever install or run any 3rd party "cleaning", "optimizing", "speed-up", anti-virus, VPN or security apps on your Mac.  This documents describe what you need to know and do in order to protect your Mac: Effective defenses against malware and other threats - Apple Community and Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support.  

There are no known viruses, i.e. self propagating, for Macs.  There are, however, adware and malware which require the user to install although unwittingly most of the time thru sneaky links, etc.   

Anti Virus developers try to group all types as viruses into their ad campaigns of fear.  They do a poor job of the detecting and isolating the adware and malware.  Since there are no viruses these apps use up a lot of system resources searching for what is non-existent and adversely affect system and app performance.

There is one app, Malwarebytes, which was developed by a long time contributor to these forums and a highly respected member of the computer security community, that is designed solely to seek out adware and known malware and remove it.  The free version is more than adequate for most users.  

Unless you're using a true VPN tunnel, such as between you and your employer's, school's or bank's servers, they provide false security from a privacy standpoint. 

I recommend you uninstall any A/V and other apps that fall in to the categories in the first sentence of my reply according to the developers' instructions.

Thank you this notification has been annoying me. Your explanation to the solution was perfect.

This literally just happened to me last night! I've never seen the pop up before, so it almost got me, but thankfully I did research first. None of my antivirus apps said there was any issue either. This is definitely one of the most sneaky scams I've seen with how official they make it look. Taking a closer look at the warning, the grammar & punctuation were a bit off, so that was a helpful sign lol

One of my favorite scam pop ups ever had the line: "You broke the internet."

It was an easy fix. Just a notification issue. 👍