title: Suppress errors in Symfony 2
body: <p>I try to remove some fields from form in event listener. But when I do that I get an error like <code>this form should not contain extra fields</code>. How can I suppress this error?</p>
  
  <p>Here is my listener:</p>
  
  <pre><code>$builder-&gt;addEventListener(FormEvents::PRE_SUBMIT, function (FormEvent $event) {
          $form = $event-&gt;getForm();
          $form-&gt;remove('field');
          }
      });
  </code></pre>