Windows automatic update is a good thing except when an update is installed that requires a reboot and you're working on the computer at the time. Then you get the "Restart now or Restart later" dialog.It can't be dismissed.
If you You get two choices, Restart Now, or Restart Later. If you click Restart Later, it pops up again ten minutes later. This belongs to wuauclt.exe, (MS's automatic update provider).
Try any of these two methods.
After update, go to Manage, Services and Applications, Services and look for Automatic Updates service. From up left click on stop service.
Note, the service from default is on automatic mode.Let it as is. Or you can stop it with a command.
Go to Start -> Run... and type net stop wuauserv (type net start wuauserv for starting it again).
After the service is stopped, the popup stops, too. Then you can reboot when you have time. The service will restart when you reboot (Automatic mode).
Go to Start -> Run.. and type: gpedit.msc. Under Computer Configuration -> Administrative Templates -> Windows Components
look for Windows Update.
Configure Automatic Updates : Choose option 4, and set install time.
Allow Automatic Updates immediate installation : Enabled
Now there are two settings and both will work, so it's your choice.
Either enable No auto-restart for schedule Automatic Updates installations or set Re-prompt for restart with scheduled installations to a long time interval, like 1440 minutes.
Either set the No auto-restart for scheduled Automatic Updates installations to Enabled or set the Delay restart for scheduled installations to Enable and Set timer to a long time interval, like 1440 minutes.