What's the MEL command to turn it off, you mean? Cos the type is a bool....

The command is:

camera -e -displayFilmGate $filmGate -displayResolution $resGate -overscan $overscan $camName;

where $filmGate and $resGate are booleans (true/on/1 or false/off/0), $overscan is a float and $camName is the name of the camera.