Undefines an AutoLISP function symbol so it is no longer available to ObjectARX applications
(vl-acad-undefun 'symbol)
Arguments
A symbol identifying a function.
You can use vl-acad-undefun to undefine a c: function or a function that was exposed by vl-acad-defun .
Return Values
T if successful; nil if unsuccessful (for example, the function was not defined in AutoLISP).