TfsConfig collection /attach /collectionDb: ; /collectionName: /clone Attaches a detached collection database. If collectionName ...

TfsConfig collection /attach /collectionDb:; 
                    [/collectionName:] [/clone]

            Attaches a detached collection database.
            If collectionName is specified then the collection will be renamed
            to the new name and the name will also become the new 
            virtual directory for the collection.
            If the clone option is specified then this collection will be 
            created as a clone of the original detached collection.

TfsConfig collection /detach /collectionName:

            Detaches a collection from the Team Foundation Server.
            The collectionName parameter is required and specifies
            which collection will be detached.

TfsConfig collection /delete /collectionName:
    
            Permanently deletes a collection from the Team Foundation Server.
            The collectionName parameter is required and specifies
            which collection will be deleted