Pondus
3
It is not a virus, it is a HTML:FakeAlert >> https://myonlinesecurity.co.uk/some-videos-of-typical-tech-support-scams/
If you have the URL avast can add it to URL block
AdwCleaner should clear your browser > https://www.malwarebytes.com/adwcleaner/
If still a problem, follow instructions Eddy gave link to