Remove a function from the list of functions to be registered
void RemoveFnA( LPCSTR pszFnName );
Pointer to a null-terminated string containing the exported name of the function (i.e. the name visible in Excel).
Removes the named function from the list of functions that will be registered when RegisterFunctions() is called during the OnXllOpen() event.
This function should only be used before RegisterFunctions() is called, preferably during the OnXllOpen() or OnXllOpenEx() event handlers.