Remove the field with the received field name from model.

def remove_field(self, field_name):
        """Remove the field with the received field name from model."""
        field = self._fields.pop(field_name, None)
        if field is not None and field.default is not None:
            if six.callable(field.default):
                self._default_callables.pop(field.key, None)
            else:
                self._defaults.pop(field.key, None)