code: public synchronized void destroy() throws IOException {
      if (mState == State.DESTROYED) {
        return;
      }
      if (!mSuccess) {
        saveWorkdir();
      }
      mCloser.close();
      LOG.info("Destroyed cluster {}", mClusterName);
      mState = State.DESTROYED;
    }
docs: Destroys the cluster. It may not be re-started after being destroyed.