remove method
      
Object3D?
remove(
    
- Object3D object
inherited
    Removes object as child of this object. An arbitrary number of objects
may be removed.
Implementation
Object3D? remove(Object3D object) {
  final index = children.indexOf(object);
  if (index != -1) {
    object.parent = null;
    children.removeAt(index);
    object.dispatchEvent(_removedEvent);
  }
  return this;
}