Delete Visual Studio Server Explorer Connections

The short, the file is located at C:\Users\<username>\AppData\Roaming\Microsoft\VisualStudio\10.0\ServerExplorer\DefaultView.SEView.  It is a plain XML file and can be edited by hand to remove the offending entries and is located in the Roaming sub-folder even if you are not on a roaming profile.

For more info, see the original article I found the location on.