Try to use this maxscript:
Code:
function killMenu str = (
m = menuMan.findMenu str
if m != undefined do menuMan.unRegisterMenu m
)
killMenu "FurryBall RT"
killMenu "FurryBall - Materials"
killMenu "FurryBall - Lights"
killMenu "FurryBall - Environments"
killMenu "FurryBall - Import/Export"
killMenu "FurryBall - Utilities"
killMenu "FurryBall - Help"