I may be a little late to the party, but here's the fix:
The problem lies with a missing XML file from groove.
To fix it, copy the setup.xml from the groove folder of the installation source, and paste it in C:\Program Files\Common Files\Microsoft Shared\OFFICE14\Office Setup Controller\Groove.en-us\
Now run the uninstaller again

I've attached the x86 and x64 setup.xml's for your convinience, just unzip the .rar and copy the appropriate file