Removing malware used to be fairly easy, at least in principle. Detect the infection, kill any running processes and files, and that’s it – finished.
These days, unfortunately, life can be more difficult. Some malware will actively try to block any attempts to remove it, perhaps preventing you from running antivirus tools, locking its files, maybe restarting itself if necessary. This can be frustratingly effective, too, but there are ways to fight back. And KillEmAll is a great place to start.