Unexpected popup won't go

Hello Susan.
Could you please share a screenshot ( http://avgclick.me/createascreenshot ) of the pop up you are receiving?

A white background unattributed window has appeared offering a Free Scan. I don't know how to get rid of it and AVG didn't block it. The is no "close" option. Help please

Hello Susan.
Could you please share a screenshot ( http://avgclick.me/createascreenshot ) of the pop up you are receiving?