If you tried to install a 64-bit or 32-bit version of Office 2016, Office 2013, or an Office standalone application such as Visio on a computer that already has either the 32-bit or 64-bit version of Office, you could see one of the following error messages. This occurs because you can't mix 64-bit and 32-bit versions of Office.
Decide which version to install
To switch from 32-bit to 64-bit, you must first uninstall the 32-bit version and then install the 64-bit version. Likewise, to switch from 64-bit to 32-bit, you need to uninstall the 64-bit version and then install the 32-bit version.
Step 1: Uninstall Office
Uninstall the version of Office or stand-alone Office application, such as Visio or Project you don't want. See Uninstall Office from a PC.