I used sometimes ago a PowerShell command that makes an installed version of MS Office to revert to an older version, any of those referenced at Update history for Office 2013
But I don't remember the command, can you help?
The procedure was to launch PowerShell as an admin.
Then execute a command starting from somewhere into C:\Program Files\Microsoft Office 15\root\office15\
and ending with =[the version you want to go to]
(like =15.0.4823.1004)