private void removeFlagFile(String flagName){
  File flagFile=new File(dbDir,flagName);
  if (flagFile.exists()) {
    flagFile.delete();
  }
}

private void removeFlagFile ( String flagName ) { File flagFile = new File ( dbDir , flagName ) ; if ( flagFile . exists ( ) ) { flagFile . delete ( ) ; } }
remove given flag file under dbdir
