Use the command line utility TF - Team Foundation Version Control Tool (tf).
You can get a list of all workspaces by bringing up a Visual Studio Command Prompt then changing to your workspace folder and issuing the following commands:
C:YourWorkspaceFolder>tf workspaces /owner:*
You should see your problem workspace in the list as well as it's owner.
You can delete the workspace with the following command:
C:YourWorkspaceFolder>tf workspace /delete /server:BUILDSERVER WORKSPACENAME;OWNERNAME
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…