Can you help me with alpha antivirus on my husband's computer?

What do we do? My husband’s computer got a pop up saying it is infected with the alpha antivirus and that he has trojans or something? He could not uninstall. He is trying a scan with our trend micro but the scan seems to be going faster than usual and is not finding anythng. I googled alpha antivirus, but am not clear what to do, because I don’t know what to trust.

Help!