Had another look at the manuals, thanks for the links. In the end I reset the control unit, 25 presses of f4! This cleared the command stack but I still have some loco's on the LH100 handsets which do not want to clear? The good news seems to be that the loco's on my iPhone Touchcab "stack" are all still there so I have not lost the additional data for sound, names etc that Touchcab allows. I reckon I have cleared at least 100 addresses so a good result.
Thanks for the responses
Trev