I also had this issue until I sat down and figured out how to make Windows Update stop forcing Windows 10 on me. Basically, you need to remove KB3035583, hide it from updates AND uncheck the box to "give me recommended updates the same way I receive important updates". Otherwise, it would keep coming back.
This latest patch Tuesday also introduced another "update" to trigger Win10 installation, it's called: upgrade to Windows 10 Pro, version 1511, 10586
Hiding that in Windows Update got me back to installing the normal updates.
Microsoft is making this whole process way too painful for those of us who know we don't want to update.
Basically, the way they're going, it's only a matter of time before Win 7 & 8 basically don't work anymore.
I've "hidden" KB3035583 half a dozen times in the last year (even posting here about how ridiculous this all was and being promptly flamed to ashes). It always comes back eventually.
I'm pretty sure even an update changed from recommended to important will stay hidden too. Though, I wouldn't be surprised to learn that can be overridden.
At least Windows Update makes it obvious when it (Windows 10 installer) returns in some form.
EDIT: clarified last line.
Eventually they'll just start obfuscating what an update does on the website as well, if not lying outright.
There's no grand conspiracy here. Put the tinfoil hat away...
When I'm lied to about updating, and it takes bloody forever normally, it pisses me off. When you start trying to hijack my machine for your purposes "for Win10", you can collectively fuck off.
I'll set on my Windows Machine (yes singular, all others are Linux variants) for No-update Windows 7. And I'll also switch everyone I know to no-update as well.
I don't know which, and don't really care. Either way, there's a case to be made for disabling updates entirely.
I've actually had the "opposite" problem. Ever since Win10 came out, my Win7 machine doesn't bother announcing when updates are available. I have to remember to install them myself ever "patch Tuesday".
But I repeat: this is madness. What kind of a psycho update mechanism would try to install an new OS behind your back?