I ran that GWX Control Panel program on 3 PCs and haven’t seen a Windows 10 nag since. I’d recommend it.
http://blog.ultimateoutsider.com/2015/08/using-gwx-stopper-to-permanently-remove.html
My elderly aunt is getting the Win 10 nag now, too. I need to go over there & put it on her computer - it’s certainly stopped the ‘nag’ on the two laptops in our house AND gotten rid of all the files Microsoft downloaded on my laptop after I foolishly reserved for Win 10 & then changed my mind. Glad it’s worked for you! :-)