private static synchronized void remoteTearDown() {
    try {
      DistributionMessageObserver.setInstance(null);
      destroyRegions(cache);
    } finally {
      try {
        closeCache();
      } finally {
        try {
          cleanDiskDirs();
        } catch (Exception e) {
          logger.error("Error cleaning disk dirs", e);
        }
      }
    }
  }
Local destroy all root regions and close the cache.
geode-dunit/src/main/java/org/apache/geode/test/dunit/cache/internal/JUnit4CacheTestCase.java