Step 5. Get rid of the GWX (Get Windows X) patches. Back in Control Panel, Add or Remove programs, on the left click View installed updates. Look for KB 2952664 (likely on Win7 systems) and KB 2976978 (likely on Win 8.1). Also look for KB 3035583 (both Win7 and Win 8.1). If you find any of them (hint: click the column heading to sort alphabetically), click on it, and click Uninstall. (t/h EP)
Step 6. Reboot. Windows will prompt you to reboot. Do it. And wait. And wait. It may take an hour to reboot.
Step 7. Permanently disable the GWX patches. The minute you've rebooted, go back in to Windows Update and "hide" KB 2952664, KB 2976978, and/or KB 3035583. To hide them, run Search for Updates, right-click on the entry and choose Hide. (t/h CT)
Step 8. For good luck, reboot again. That probably isn't necessary, but it'll kill off any process that thinks it should be downloading the Windows 10 installation files.
On the systems I've tested, that'll remove the downloaded Windows 10 files, the obnoxious nags in the system tray, and the "Your upgrade to Windows 10 is ready" notification in Windows Update. I'm not absolutely sure it'll work in all cases, but the worst case is you've lost some time -- you aren't twiddling with any registry settings or doing anything that might cripple your Win7 or Win8.1 system. It's strictly a home remedy, but Microsoft certainly isn't going to distribute a magic fix.
Suggestions and in-the-wild status reports most welcome. Hit me in the comments.
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