Uninstall AVAST from MacBook Pro

Avast arrived somehow to my computer but I did not choose it and I immediately went to uninstall it. Their uninstall program asks for your MAC ID. I'm not about to give that to anyone online. Is it possible to uninstall if in any other way? How can it be a legitimate company if you can't get in touch with them and have to put your password online. I think it is a scam. Ideas or experiences, anybody?