Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Uninstall office completely using theKB 928218
Note: make sure you take a backup of the registry, also read the disclaimers carefully before making the changes.
Then use a new windows user account created as administrator to install office. Once office is successfully installed, you may delete the new windows user account created. Check the link below for information on creating user accounts:
http://windows.microsoft.com/en-US/windows7/Create-a-user-account
Sachin Shetty