Remove field type from symfony form using PRE_SET_DATA event

FormController.php

<?php

namespace Acme\AppBundle\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Template;

use Acme\AppBundle\Form\RemoveType;

class FormController extends Controller
{
    /**
     * @Route("/form/remove")
     * @Template()
     */
    public function removeAction()
    {
        $data = array('foo' => 'FOO');

        $form = $this->createForm(new RemoveType(), $data);

        return array('form' => $form->createView());
    }
}

remove.html.twig

{% extends "::base.html.twig" %}

{% block body %}
{#    {{ form(form) }}#}
    {{ form(form.foo) }}

    {% if (form.bar) is defined %}
        {{ form(form.bar) }}
    {% endif %}
{% endblock %}

RemoveType.php

<?php

namespace Acme\AppBundle\Form;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\Form\FormEvent;
use Symfony\Component\Form\FormEvents;

/**
 * @author Michael Borchers <[email protected]>
 */
class RemoveType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('foo')
            ->add('bar')
        ;

        $builder->addEventListener(FormEvents::PRE_SET_DATA,
            function (FormEvent $event) {
                $data = $event->getData();
                $form = $event->getForm();

                $form->remove('bar');

                dump($data);
        });
    }

    public function getName() {
        return 'remove';
    }
}