change comment form container to textarea How to remove the red section in next image (comment form)?



I have try change the type to textarea, but on submit the form a blank page appears.

function THEME_form_comment_form_alter(&amp;$form, &amp;$form_state) {
    $form['comment_body']['#type'] = 'textarea';
}
You can make the field plain text in the comment body field settings.

e.g: 

http://example.com/admin/structure/types/manage/article/comment/fields/comment_body 


  "Text processing" > "Plain text"