Removing Quincy, Bug Report and Battery Report.
Since I have just tried this myself and it works, I will post up instructions for those who are interested. Proceed at your own risk!
Using Windows explorer, navigate to C:/Program Files/Common Files/Research In Motion/RIMInternalTools-184.108.40.206/Java/
Delete the following files:
With your device connected, start up Desktop Manager (I'm using v4.5)
Click on Application Loader and then Add/Remove Applications. This should do a search for updated applications and then list everything installed onto your phone.
Click the Finish button at the bottom right. You SHOULD see a screen that shows the following files listed above will be removed from your handheld and then click OK. It will proceed to remove the files and then restart your Berry.
FYI: If you are going to install a beta OS there is an option to uncheck this before you hit finish on your Desktop Manager.
Thanks to AUtigers350z for the write up.