code: public static void unregisterObject(String id, Object obj) {
      DefaultMonitorRegistry.getInstance().unregister(newObjectMonitor(id, obj));
    }
docs: Unregister an object from the default registry. Equivalent to
  {@code DefaultMonitorRegistry.getInstance().unregister(Monitors.newObjectMonitor(id, obj))}.
  
  @param obj Previously registered using {@code Monitors.registerObject(id, obj)}