Delete
        Puts model for deletion into unit of work and optionall commits
        transaction

        :param model:           object, model to delete
        :param commit:          bool, commit?
        :return:                object, deleted model

def delete(self, model, commit=True):
        """
        Delete
        Puts model for deletion into unit of work and optionall commits
        transaction

        :param model:           object, model to delete
        :param commit:          bool, commit?
        :return:                object, deleted model
        """
        self.is_instance(model)
        db.session.delete(model)
        if commit:
            db.session.commit()

        return model