Help! How to turn off sound notifications for Windows Mobile Updates

Hi. Have a 950XL with Win10 Mobile which works great. Not on any insider rings. The phone was set to system update automatically which it did last night, in the middle of the night. It restarted with a beep and woke me up! I'd previously had it set to manual update which had beeped in the middle of the night to tell me to set a time to update. Is there any way to remove sound notifications for system update so I can get a good nights sleep?

Go to Settings > Personalization > Sounds. Uncheck the "System alerts" option. Else just set your phone to silent.