Good thing Win7 is still used for businesses, so MS has to include some way to disable Win10 upgrade stuff (though it has been walking a fine line in that scenario already). When making updated Win7 images via sysprep I've not installed the various Win10 Upgrade updates, plus in the reg tweak file I have applying at firstlogon there are tweaks to disable Win10 upgrades so I never get bothered by it. Of course people could also use "Never10" for which I made a ppApp some time ago. That Win10 upgrade icon in the system tray that most people get is actually GWX.exe running in the background, which is part of a Win10 upgrade update. If you want a more thorough measure you could load a WinPE and delete the GWX files in Windows\System32\GWX\GWX.exe (and/or SysWOW64) and combine that with the Never10 tweaks. But yeah, no doubt MS keeps ramping up their Win10 scheme and it's getting pathetic, frankly.
Also, "GWX Control Panel" work great too. It's what I've been using to stop this insanity. (http://blog.ultimateoutsider.com/2015/08/using-gwx-stopper-to-permanently-remove.html)
I've never tried myself, but if no way existed to disable GWX I would use a trick I discovered when a virus was trying to re-install itself as I closed either of it's 2 processes: make a blank text file and remove the .txt extention: C:\windows\system32\gwx Then right click it and make it read only and disable all user access except Administrator (NOT Administrators) then nothing can delete it and the sub files/folders can never be created, I think I crashed the virus by doing this and I was able to close both processes
There is an app called autorun antivirus that does something similar that prevents autoun virus from infecting your system. It creates an autorun.inf directory and makes it read only and changes permissions.