def parse_user_unassign_sync_agent_data(json):
    """
    Parse the incoming statement for a sync agent event concerning a user role unassignment.

    :param json: A statement concerning a user role unassignment that needs to be synced.
    :type json: union(dict(str, NoneType), dict(str, dict(str, str)))
    :return: A dictionary containing a user id, a course id, and the unassigned role for that course.
    :rtype: dict(str, str)
    """
    statement = json['statement']
    role = statement['object']['definition']['name']['en']
    course_id = statement['object']['id'].split("=")[-1]
    user_id = statement['actor']['account']['name']
    sync_unassign_role_data = {
        'role': role,
        'course_id': course_id,
        'user_id': user_id,
    }
    return sync_unassign_role_data