download and install these and run scans
https://www.avast.com/en-au/free-antivirus-download
https://www.malwarebytes.com/mwb-download/
or reinstall windows
Yes you can still get audio in through HDMI as it does both video and audio. There is also composite which is the red yellow and white connectors these also have video and audio.
It may hang around longer if the drive you booting off isn't at the top of the boot order, you can change this by getting into the bios. But i doubt there's a way to get rid of it entirely.
My personal preferance is Avast. Simple, easy to use and you can just let it run in the background and not have to think about it other than to do an occasional virus scan.
https://www.avast.com/en-au/index
Go to where the installation was made (probs C:\Program Files (x86) or C:\Program Files) and find the progams folder. In that folder there should be a uninstall .exe just click that.