The update that is responsible for the Get Windows 10 utility is caused by Windows Update item KB3035583.
To remove this update, go to the Control Panel and open Windows Update. In the bottom-left corner of the window, select Installed Updates (see screenshot below), search for KB3035583, right-click on it and select Uninstall. You'll be asked to restart your computer after removing the update.
(Screenshot from howtogeek.com)
Once it's removed, you need to prevent the update from being potentially reinstalled. To do this, navigate back to Windows Update, search for available updates (it might take a while), then see a list of all the available updates, find the update labeled KB3035583 at the end, right-click on it, and select Hide update. This will prevent the update from being reinstalled until you unhide it.
To restore any hidden updates, just go to the Restore hidden updates from the left section of Windows Update.