Most viruses can be removed, but usually not with a single virus scanner. It takes multiple scanners to remove most of the viruses. So when you get a virus, it has already bypassed your current virus scanner and you need to use multiple other scanners. Usually this will remove most if you use a quality scanner. One of the scanners that we use is MalwareBytes. This free scanner will remove a lot of the nasties that you will encounter, but again not all.
If you would like to know more of the tools, please visit Computer Virus, Spyware, Malware, Key Loggers, Trojans and Rootkit Removal.