Sorry. I hadn't replied earlier to your question. I wanted to back up the Office installation itself. I was not worried about the .docx, .dotx, .xlsx files etc. that I'd created. I knew they were in safe locations on the drive.

It's all good now. Via the Control Panel, I crossed my fingers and "removed" Office 365. It took the Office 2016 along with it. And my Office 2013 now works as it did before all this. No problems.