I haven’t tried it, but several reputable websites (I’ll post links afterwards) have each recommended downloading and running this:
https://www.grc.com/never10.htm
https://www.grc.com/never10.htm
References:
http://www.howtogeek.com/218856/how-do-you-disable-the-get-windows-10-icon-shown-in-the-notification-tray/
http://www.pcadvisor.co.uk/how-to/windows/how-stay-on-windows-7-8-forever-stop-upgrade-notifications-3614204/
http://www.pcworld.com/article/3048836/windows/never10-is-a-free-app-for-when-you-absolutely-positively-dont-want-windows-10.html
You can also do it manually if you’re more comfortable going through the steps. Each of those sites shows a manual process and you can compare.
I’m also on Windows 7 and plan to stay on it until this laptop dies of natural causes. [it’s on its 2nd keyboard already]. I’ve got everything configured just how I like it. I’ve been lucky that I’d disabled Automatic Updates a long time ago, so I never received the Win10 upgrade nag, although I’m sure I missed some useful upgrades in the process. I like having control over my PC and since all of my favorite useful tools and programs are Windows, I really don’t feel like going through the hassle of moving over to Linux at this point. Maybe later but for now, I rather like Windows 7