Hi,
I am not a moderator, just another person who had what you have. I bought a brand new machine with Windows 10 on it. First boot, I got that thing from Avast, which I found strange as Avast had not been loaded onto the computer by me. Then I realized that Avast had a app installed on my machine. It did exactly what you said yours did. When I clicked the box to stop trying to sell me something, the popups just got worse. I went to settings, I think, and just removed the app. As far as I am concerned, this was bloatware, courtesy of Avast. I was using Avast since 2004, but this was too much for me. I have switched to Panda. Much lighter on the system and it gets very good reviews.