Like many others it seems, when uninstalling the Windows Phone Dev Tools CTP I uninstalled each of the individual components before getting to the actual “Microsoft Windows Phone Developer Tools CTP – ENU”. When this happens the uninstall doesn’t work, unless you first re-install everything else.

Or, thanks to Nick Berardi, you can just navigate to the install folder (C:Program Files (x86)Microsoft Visual Studio 10.0Microsoft Visual Studio 2010 Express for Windows Phone  CTP – ENU is the default), right click on vs_setup.msi and select Uninstall from the menu.

It works great, and is much better than redownloading the CTP and reinstalling first.

Now, back to installing the XNA Game Studio 4.0 Beta!