Poisoned MacAir

I have a MacAir running on Yosemite.
Suddenly I get plenty of unwanted popup windows showing, dancing, strutting here and there. When I click on the X to close them they actually send me to an unwanted publicity page.
How can I remove all these plugins?
I am running Avast for Mac and Clean my Mac2.
However I suppose it needs some sanitizing.
Any suggestions. Thanks.

AdwareMedic
That should fix it.

Also, get rid of Clean my Mac and Avast. They are not doing you any good.
http://www.mac-forums.com/forums/sw...-official-antivirus-malware-firewall-faq.html

Indeed, that's probably where the adware came from in the first place.