/For=ForVolumeSpec /On=OnVolumeSpec /Quiet - Deletes an existing shadow copy storage association between ForVolumeSpec and ...

%1 %2 /For=ForVolumeSpec [/On=OnVolumeSpec] [/Quiet]
    - Deletes an existing shadow copy storage association between 
    ForVolumeSpec and OnVolumeSpec.  If no /On option is given, all shadow 
    copy storage associations will be deleted for the given ForVolumeSpec. 

    Example Usage:  vssadmin Delete ShadowStorage /For=C: /On=D: