How do I stop virus notifications on my Mac after attempting to install ChromeOS Flex?

HELPPPPPPPPPP.

My Mac has been getting notifications about viruses and this has been going on for about a month now. It looks fake but it is coming off of safari wile I tried to install ChromeOS Flex on chromeOS and I needed to format and then I went on my Mac to install a formatting app but it didn't work and now I keep getting the same notification about viruses

[Re-Titled by Moderator]

Original Title: Viruses