Q: How do you remove a virus

Exactly what is happening? It may been many things, but definitely not a virus.

There are no viruses that can attack Mac.OS X. So, anti-virus programs are selling a cure for a disease that doesn't exist. And they are renowned for borking Mac systems.

A Mac can pick up malware but not if you just use common sense. You really have to actively invite some malware in for it to happen. That means downloading and knowingly giving your password for it to download. Mac provides all the protection you need with SIP (System Integrity Protection).I About System Integrity Protection on your Mac - Apple Support

If you do happen to download malware you can use MalwareBytes to get rid of it. Malwarebytes was developed by one of our own colleagues here in ASC. It gets rave reviews and is about the most proven anti-malware software for Mac. If you use torrents, don't. Torrents are a good way to pick up malware because it can hitchhike in on a download package and you’ll never know it.

Safari pop-ups are different and easier to deal with. In Safari 9.1 and later just close the window. For earlier versions force quit and hold the shift key while restarting Safari.

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

Finally, stay away from programs that purport to "clean your Mac". They can do damage to your system. Your Mac needs no cleaning in the first place. All the cleaning that is necessary is taken care of routinely by OS X.

On the list of things to avoid, I would add download sites such as softonic, cnet, and macupdate. Adware is sometimes bundled with otherwise legitimate updates on sites such as these. Only download apps from the developer's site or from the App Store.

kahjot wrote:

 

On the list of things to avoid, I would add download sites such as softonic, cnet, and macupdate.

Excellent point, kahjot.