Open CMD as administrator

Copy the following two lines in to the Command Prompt. For line 2 replace the XXX and yyy with the version of MS Office you want to roll back to that you will find in the link below.

1. cd %programfiles%\Common Files\Microsoft Shared\ClickToRun
2. officec2rclient.exe /update user updatetoversion=16.0.XXXXX.yyyy

https://learn.microsoft.com/en-us/officeupdates/update-history-microsoft365-apps-by-date

3. If you need to disable MS Office updates then open Word, click on File, Account, Update Options and click Disable Updates.