Google search results tell me that many others are unsure too, including the Microsoft forum which advised a user to delete the “com.microsoft.word†folder (doesn’t exist on my system) or reinstall Office.
I'm quite interested in seeing how you get this resolved as my Word and Excel are 32 bit and I've been thinking about the standalone Office as one option for getting to Mojave. I wonder if the com.microsoft.word does exist on your drive but is invisible. It might be worth checking. I'm High Sierra and this process works for me to make invisible files visible.
1 Double-click your Macintosh HD icon to see all the visible files and folders on your drive.
2. Hold down Cmd + Shift + . (Period)
3. All the invisible files will also become visible
4. Hold down Cmd + Shift + . (Period) again to re-hide the files
If the com.microsoft.word file is revealed, you'll be able to drag it to trash.
