1. In Outlook >File >Office Account >Update Options >Disable Updates.
2. Run the Command Prompt as Administrator.
3. Choose your version number from this list:
4. Replace xxxx.yyyy with the build number you want to revert to.
"C:\Program Files\Common Files\microsoft shared\ClickToRun\officec2rclient.exe" /update user updatetoversion=16.0.xxxx.yyyy
5. When Office has finished updating, you may need to run a Quick Office Repair (**Do Not perform an Online Repair).
6. When completed, check your version to verify it updated properly.
Note: you may be required to verify your license number again.