protected void closeDown(Region region) {
    try {
      if (!region.isDestroyed()) {
        region.destroyRegion();
      }
    } catch (Exception e) {
      logWriter.error("DiskRegionTestingBase::closeDown:Exception in destroyiong the region",
          e);
    }
  }
cleans all the directory of all the files present in them
geode-junit/src/main/java/org/apache/geode/internal/cache/DiskRegionTestingBase.java