Symfony 2 delete record from database on button click based on checkbox

I have messages listed on the page. Messages have their ids. I want to delete checked (checkbox) messages on button click.

Here is the controller action that deletes a single record:

/**
 * @Route("/{_locale}/profile/inbox/delete", name="inbox_message_delete")
 */
public function deleteMessages(Request $request)
{
    $em = $this->getDoctrine()->getManager();
    $msg_id = $request->request->get('message-checkbox');
    var_dump($msg_id);
    $message = $em->getRepository('MyBundle:OfferMessages')->find($msg_id);

    $em->remove($message);

    $em->flush();

    return new Response('O.K.');
}

My form looks like this:

<form action="{{path('inbox_message_delete')}}" method="post">

My submit button looks like this:

<input class="messages-received-delete-selected1" type="submit" value="{{'delete'}}"/>

Checkbox looks like this:

<input type="checkbox" name="message-checkbox[]" id="{{message.id}}" value="{{message.id}}" />

When I click the submit button I get the following page:

/profile/inbox/delete?message-checkbox=13492546

No var_dump() and new Response('O.K.') is shown.

How to refactor this code in order to work properly?