Reinstalling Microsoft Office is sometimes not trivial. When trying to restart the setup, a message might appear stating that Office cannot be removed. Even in the Control Panel, you cannot uninstall Office properly in such cases.
To help you uninstall Office properly, Microsoft has published a removal tool. You can download it for free from support.microsoft.com/kb/290301#FixItForMe. There, choose your Office version to remove and click the corresponding “FixIt” icon. Start the download and follow the appearing wizard. Now you can safely reinstall Microsoft Office.