deleteLink example

  protected function deleteInstance(MenuLinkInterface $instance, $persist) {
    $id = $instance->getPluginId();
    if ($instance->isDeletable()) {
      if ($persist) {
        $instance->deleteLink();
      }
    }
    else {
      throw new PluginException("Menu link plugin with ID '$id' does not support deletion");
    }
    $this->treeStorage->delete($id);
  }

  /** * {@inheritdoc} */