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

%1 %2 /Provider=ProviderNameOrId /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. 
    - The Provider ID can be obtained by using the List Providers command. 
    When entering a Provider ID, it must be in the following format:
       {XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX} 
    where the X's are hexadecimal characters.  

    Example Usage:  vssadmin Delete ShadowStorage 
                             /Provider={b5946137-7b9f-4925-af80-51abd60b20d5}
                             /For=C: /On=D: