I am sure this could be fixed somehow, but if it is a choice between doing a complete Windows 10 fresh install or leaving Office 2007 lying dormant, I'll choose the latter option, unless I come across problems in the near future. I suspect as you say, that Office 2007 has somehow got tied into Office 365. I have managed to get Office 365 fully working, but Office 2007 is still lying around. So I tried to uninstall Office 2007 which is where the problems arose. Next, locate the program you’d like to uninstall from the menu, right-click it, and then click Uninstall. Click the Windows icon in the bottom-left corner of the desktop to open the Start menu. However this was not the case as there were file association problems in Word. One of the quickest ways to uninstall a program is by accessing it through the Start menu.

I was informed by a Microsoft operative that it could be installed alongside 2007 as they use a different install process. I installed Office 365 as a trial to see if I wanted it before buying.

Yes, the list does show Office 2007 as being installed and I can select it and choose it before selecting Uninstall - but this does nothing.

Uninstall office