1. override
void detachRenderObject()

Remove renderObject from the render tree.

The default implementation of this function simply calls detachRenderObject recursively on its child. The RenderObjectElement.detachRenderObject override does the actual work of removing renderObject from the render tree.

This is called by deactivateChild.

Source 

@override
void detachRenderObject() {
  if (_ancestorRenderObjectElement != null) {
    _ancestorRenderObjectElement.removeChildRenderObject(renderObject);
    _ancestorRenderObjectElement = null;
  }
  _slot = null;
}