def delete_database(client, db_name, username=None, password=None):
    """Delete Arangodb database

    """

    (username, password) = get_user_creds(username, password)

    sys_db = client.db("_system", username=username, password=password)

    try:
        return sys_db.delete_database(db_name)
    except Exception:
        log.warn("No arango database {db_name} to delete, does not exist")