Is there anyway to stop Microsoft Office 2016 on macOS prompting for update?
Remove the "/Library/Application Support/Microsoft/MAU2.0" folder, which to place the Microsoft Auto Update (MAU) program.

Update: I found ms-office applicaiton would create the MAU2.0 and Microsoft AutoUpdate.app automatically after some days. You can create a blank file named MAU2.0 in the "/Library/Application Support/Microsoft" folder.

sudo touch "/Library/Application Support/Microsoft/MAU2.0"