public void deregisterObserver(ConfigurationObserver observer) {
    synchronized (configurationObservers) {
      configurationObservers.remove(observer);
      if (observer instanceof PropagatingConfigurationObserver) {
        ((PropagatingConfigurationObserver) observer).deregisterChildren(this);
      }
    }
  }
Deregister an observer class
@param observer to be deregistered.
hbase-common/src/main/java/org/apache/hadoop/hbase/conf/ConfigurationManager.java