You can delete a TFS branch from the Visual Studio Developer Command Prompt, using the 'tf destroy' command. The syntax is as follows:

C:\tf delete $/TeamProject/Branch

This is also valid for folder or files.

C:\tf delete $/MyTeamProject/Folder
C:\tf delete $/MyTeamProject/Folder/File

Of course remember to put any Branch/Folder/Files with spaces in, inside quotes:

C:\tf delete $/MyTeamProject/"Branch No 1" 

As always, feel free to comment, or ask.