Unassigning a router output?

Hey folks,
All of our rooms are built in NWare with routers to assign inputs 1-100 to a number of outputs (typically 1 to 3).  We are trying to figure out how to unassign the outputs, i.e. if we are overflowing an audio+video source to another room, and someone logs out of the Crestron touch panel in the source room, we want to unassign all audio and video that might have been left overflowed to other rooms.

Is there a command or value to remove the input assignment from a given router output or does it always have to be assigned to something? Our fallback is to designate an unconnected router input the "mute" input so we can assign that to the output that we want to silence, but I'd rather figure out if we can unassign the designated output.

Thanks,
Jeff