How to reverse my previous update made to my MAcBook Pro Yosemite OS X10.10.5
On July 16, 2016, I updated my adobe flash player. After that moment I had an ads appearing in my tool bar which named is Megabackup continually popup on my screen all the time. I tried to delete it but without success. My question is how to restore my system to the state it was before this updating? Thank you.
Mac Pro, OS X Yosemite (10.10.5)