code: public static void stop(Context context, String clientId) {
          Intent intent = new Intent(context, PlaybackService.class);
          intent.setAction(ACTION_STOP_PLAYER);
          intent.putExtra(BUNDLE_KEY_SOUND_CLOUD_CLIENT_ID, clientId);
          context.startService(intent);
      }
docs: Stop the SoundCloud player.
  
  @param context  context from which the service will be started.
  @param clientId SoundCloud api client id.