This function deletes one determined field using the command MODEL.pw.delete_field(FIELD)

    Args:
        field_name (string): This argument let you delete some field for some model registered in the index.

    Returns:
        (WhooshSchema): The new schema after deleted is returned.

def delete_field(self, field_name):
    """This function deletes one determined field using the command MODEL.pw.delete_field(FIELD)

    Args:
        field_name (string): This argument let you delete some field for some model registered in the index.

    Returns:
        (WhooshSchema): The new schema after deleted is returned.
    """
    self._whoosh.remove_field(field_name.strip())
    return self._whoosh.schema