How to Uninstall Microsoft Office 2010 Technical Preview
Microsoft Office 2010’s public beta just leaked on peer-to-peer file sharing. Prior to installing the latest beta, you must uninstall the previous version of Office 2010. If you try uninstalling it, you’ll be greeted with this error message:
“This product installation has been corrupted. Please reinstall from original CD or source.â€

According to Vikas Narula from Technet, the problem is cause by a missing file from the installation folder of Office 2010:
“To uninstall Office 2010 14.0.4302.1000 if you have an uninstall error message "This product installation has been corrupted". The Problem is a missing file in the installation folder of office 2010. Office 2010 as a Setup Controller directory and uses the directory to check the installed components. Please check he directory "C:\Program Files\Common Files\Microsoft Shared\OFFICE14\Office Setup Controller\Groove.en-us\". if you have no "Setup.xml" file there please copy the file from the "Groove.en-us" directory of the source files to this directory and test the uninstallation againâ€
To fix this issue, right click and save setup.xml to your computer and copy it to this folder:
C:\Program Files\Common Files\Microsoft Shared\OFFICE14\Office Setup Controller\Groove.en-us\
Now try uninstalling Office 2010 Technical Preview.