def METHOD_NAME(user_id):
    """
    Delete a user if they exist.
    Parameters
    ----------
    user_id : int
    Notes
    -----
    You cannot delete the _final_ admin user.
    """
    user = User.query.filter(User.id == user_id).first_or_404()
    if user.is_admin and len(User.query.filter(User.is_admin).all()) == 1:
        raise InvalidUsage("Removing this user would leave no admins.")
    db.session.delete(user)
    db.session.commit()
    return jsonify({"poll": "OK"})