Mark one event channel as non exported in database

        :param argin: name of event channel or factory to unexport
        :type: tango.DevString
        :return: none
        :rtype: tango.DevVoid

def DbUnExportEvent(self, argin):
        """ Mark one event channel as non exported in database

        :param argin: name of event channel or factory to unexport
        :type: tango.DevString
        :return: none
        :rtype: tango.DevVoid """
        self._log.debug("In DbUnExportEvent()")
        event_name = argin[0].lower()
        self.db.unexport_event(event_name)