start_sf5_project/app/templates/beer/_delete_form.html.twig

<form method="post" action="{{ path('beer_delete', {'id': beer.id}) }}" onsubmit="return confirm('Are you sure you want to delete this item?');">
    <input type="hidden" name="_method" value="DELETE">
    <input type="hidden" name="_token" value="{{ csrf_token('delete' ~ beer.id) }}">
    <button class="btn btn-{{ btn_color|default('danger')}}"><i class="fa fa-trash fa-fw"></i> {{'Delete'}}</button>
</form>