(1) Try canned malware removal tools (several will be suggested in this thread).
(2) When that fails, schedule an afternoon to work on it, go to www.majorgeek.com, and exactly follow their instructions for dealing with viruses and malware. (It’s all free, but will take a while. And when I say “exactly,” I mean EXACTLY. You will be messing with dangerous parts of the OS. A mistake WILL nuke it.)
My dad had that on his computer. One does have to follow the directions for removal EXACTLY. But it does work. At least he didn’t click on the link to pay for the program by credit card.