Unregisters the inputed walkthrough from the application walkthroug
        list.
        
        :param      walkthrough | <XWalkthrough>

def unregisterWalkthrough(self, walkthrough):
        """
        Unregisters the inputed walkthrough from the application walkthroug
        list.
        
        :param      walkthrough | <XWalkthrough>
        """
        if type(walkthrough) in (str, unicode):
            walkthrough = self.findWalkthrough(walkthrough)

        try:
            self._walkthroughs.remove(walkthrough)
        except ValueError:
            pass