I keep getting Warning of muiltiable virus and malware on my Mac. Yet I have Apple anti virus protection, is this a scam to get me to by and anti virus product.

Apple doesn't sell any type of AV software. Whatever it is you installed, remove it.

If these warnings are sliding in from the top right of the screen, a web site you visited gave itself permission to use Notifications.

Everything you're seeing is nothing but a scam.

Open Safari's preferences. Click on the Websites tab and then scroll down to Notifications. Clear any entries in the right hand window. You might find something similar in the Pop-up Windows heading below that. Block any you don't recognize.

Then if you want, uncheck the box below as shown here.

I personally can't think of any reason why I would ever want any website to push notices to me.