How to unlock a file in Team Foundation Server(TFS)

To unlock a file in Team Foundation Server you have to issue the following command at the Visual Studio Command Prompt:

TF UNDO filename /WORKSPACE:workspace;checkout_user /SERVER:servername

Where you change the lower case words with your particular case.  For more information go here:

http://weblogs.asp.net/dmckinstry/archive/2006/07/09/Undo-_2F00_-Unlock-for-Others-with-Team-Foundation-Version-Control.aspx