Remove Target Object reference from constraint with python I know how to set a constraint target via Python:

ob = bpy.data.objects["RightArmIKDataPoint"]
bpy.data.objects["MySkeleton"].pose.bones["RightArmIK"].constraints["MocapHook"].target = ob


However, I do not know how to unset this. I don't know what set the target to to be empty.
Simply set the the target property to None to clear the target field. 

So in your example it would be:

...constraints["MocapHook"].target = None