When trying to install Microsoft Office, you may have installed 32-bit version in the beginning, but want to go for the 64-bit version for some reason, you may get this error:
But hey, you know you have already removed the 32-bit version from control panel and programs and features, so what’s the fuzz all about?!
Well no need to worry, Microsoft has done the work for you, with the release of a “Microsoft Office removal tool” 
You can get it here:
Uninstall Office 2016, Office 2013, or Office 365 from a PC
Run the tool, and wait for it to complete with a green checkmark, and reboot your computer