Clears the start date.

        raise:  NoAccess - ``Metadata.isRequired()`` or
                ``Metadata.isReadOnly()`` is ``true``
        *compliance: mandatory -- This method must be implemented.*

def clear_start_date(self):
        """Clears the start date.

        raise:  NoAccess - ``Metadata.isRequired()`` or
                ``Metadata.isReadOnly()`` is ``true``
        *compliance: mandatory -- This method must be implemented.*

        """
        if (self.get_start_date_metadata().is_read_only() or
                self.get_start_date_metadata().is_required()):
            raise errors.NoAccess()
        self._my_map['startDate'] = self._mdata['start_date']['default_date_time_values'][0]