Today I decided to upgrade to the Beta of the Windows Phone Developer Toolkit, however the uninstall process wasn’t working. It kept asking me what I wanted to install every time I choose the uninstall radio button.
So after a couple failed attempts at uninstalling in different ways, I decided to go to the source, in my case that was:
C:\Program Files (x86)\Microsoft Visual Studio 10.0\Microsoft Visual Studio 2010 Express for Windows Phone CTP – ENU
After in the folder, I just had to right click on the vs_setup.msi file and select Uninstall, after that the process worked like a charm and I could then install the beta. Hope this helps someone besides me.
Beta, Windows Phone 7

It does, though I’ve already re-installed in hope that I can now uninstall. Thanks for the tip.
And as a follow-up, it does appear that if you have everything installed that you can uninstall successfully. I had uninstalled individual components leaving that particular piece for last.
Thanks for the help. I had the same problem and this fixed it. The beta bits are downloading as I type this.
thanks, i was just uninstalling all the old componants and got down to this one and ran into the same thing. thanks for saving me time so i can get the beta installed. you definitly helped!!
Thanks for the tip. This blog here has some more tips on the same subject:
http://blogs.msdn.com/b/astebner/archive/2010/07/12/10037442.aspx
Thank you very much. I was at my wits end before reading this quick link!
i had windows phone 7.1 beta and I had trouble uninstalling it. Using your suggestion I was able to install 7.1 RC
thanks
Thank you so much. it works