Try starting with the GWX Control Panel, available at http://ultimateoutsider.com/downloads/ (this can do all of what you see below and will monitor for attempts to reverse any of this)
If you want to get your hands dirty, however (and bear in mind that this is advice only, I cannot be responsible for any loss of data or system problems if you do this)...
You can also try killing the GWX process then uninstall KB3035583, then make sure that the Windows Update system is set to notify only rather than automatic download. Once that is done, there are a couple of registry keys that can be used to control the return of the nag (though I'm scepticle as to how long Microsoft will honour these).
The actual settings, if you are willing to use regedit (please remember that you do this at your own risk and hopefully would have the sense to do a registry backup first), are
If the subkey doesn't exist, simply create it then set as shown. I believe that this works for W7 and W8.x.