mupad new unit creation gives error on Evaluate all multiple times

I define a new unit with Mupad

delete kiloWHour;
unit::newUnit(kiloWHour= unit::kiloW*unit::hour)

The problem is that every time I evaluate my notebook from start it gives me an error that the unit is already defined The first delete doesn't do anything. Is this bug in MUPAD ?

Answer 1

[Walter Roberson]

If delete was going to work at all, then you would need to delete unit::KiloWHour

[timo]

nice try -_-''

Error: The identifier 'unit' is protected. [delete]

[Walter Roberson]

http://www.mathworks.com/help/symbolic/mupad_ref/unprotect.html