Can't delete a file requiring Administrator's permission when I am adm

I'm trying to get rid of the Windows 10 upgrade nag. I removed the offending Windows update but I'm still getting the nag. Another website suggested renaming Windows\System32\GWX\GWXUX.exe. I changed ownership of System32 and subdirectories from Trusted Installer to Administrators. I'm logged in as administrator but I still get a screen saying "You require permission from Administrators to make changes to this file." when I try to rename it.

Why do I get this message? How can I rename the file?

coffent said:

I changed ownership of System32 and subdirectories from Trusted Installer to Administrators.

That was not a good thing to do.

coffent said:

Why do I get this message?

Because - by default - most processes (like Explorer) will run as if they are a standard user - even when you are logged on using an admin account.

Thanks, Brink - I will try as is suggested there.
Thanks, UNI - I will change ownership back to Trusted Installer, though in that case is there any way I can make changes to files in System32?
Also, though I was using xplorer2 rather than Windows Explorer to do the renaming, I specifically ran it as an administrator and still got the message.

The entire folder structure under System32 is not supposed to be owned by the TrustedInstaller. Some folders and their files are owned by the group named Administrators. For instance, the catroot folder and its contents are not owned by the TrustedInstaller. It is a complex mixture of ownership. Unless other forum members have a better idea, I would re-install Windows 7 to get back to the security model that Microsoft designed for that important folder.

As far as the GWX folder and its files. I seem to recall that there is a KB that one can uninstall to remove it. I am not where I can test right now.

OK, thanks again UNI. Re- and un-installing KB3035583 is a simple thing so I'll try that first.

The Windows folder and all of it's sub folders should be considered read only unless you really understand what you are doing. This is a minefield for the unwary with many ways to go wrong. Think twice before making any changes. There will almost always be a better way.