Some users out there may not want to upgrade to Windows 10 (available from 29th July 2015). Here is a method on how to remove the request.
It’s possible to disable and remove the “Get Windows 10″ icon and notification window, by uninstalling the KB3035583 update, which was delivered as a recommended update to Windows 8.1 Pro, Windows 8.1, and Windows 7 Ultimate, Windows 7 Professional, Windows 7 Home Premium, Windows 7 Home Basic and Windows 7 Starter installed with Service Pack 1 (SP1) early April 2015.
You’re now free from the Get Windows 10 system tray icon and Windows 10 free upgrade offer reservation nag screen. Some people may still have remnants of the KB3035583 update’s files in %WinDir%\System32\GWX folder. In that case just delete the folder (you may need to take ownership of the folder before being able to delete it manually).
If you just want to disable the GWX (Get Windows X) app, and keep the update installed, use the Registry Editor (Regedit) to create the following registry key and value. Or, copy and paste the following code into a text file with .reg extension, and then execute it.
Let us know if you successfully removed the notification or if you need further help.