how to get rid of virus on mac

  These are scam pop-ups. 

  Force Quit Safari.

  "Press these three keys together: Option, Command, and Esc (Escape)

  Or choose Force Quit from the Apple () menu in the upper-left corner of your screen.

  Select the app in the Force Quit window, then click Force Quit"

  Launch Safari holding the shift key down.

https://support.apple.com/en-us/HT201276

  For more info:

  Section: If you see pop-up alerts or ads

  https://support.apple.com/en-us/HT204759

  https://support.apple.com/en-us/HT203987

  https://www.thesafemac.com/tech-support-scam-pop-ups/