I’m working on a project now in which a particular role is restricted to a single text format. I was surprised to find that (even when a role is restricted to a single text format) the ‘About text formats’ link still shows.

Image credit

I thought that this was confusing and unnecessary, so I decided to remove it. Here is a very simple way that I removed the link and the unnecessary box around the link.

Create a custom module and open the .module file.

.module file

function _allowed_formats_remove_textarea_help($form_element, FormStateInterface $form_state) {

  if (isset($form_element[0]['format'])) {
    // All this stuff is needed to hide the help text.
    unset($form_element[0]['format']['guidelines']);
    unset($form_element[0]['format']['help']);
    unset($form_element[0]['format']['#type']);
    unset($form_element[0]['format']['#theme_wrappers']);
    $form_element[0]['format']['format']['#access'] = FALSE;
  }

  return $form_element;
}

You’ll have to add an #after_build entry for _allowed_formats_remove_textarea_help() to each textarea fvalue in whichever form(s) you want to hide the ‘About text formats’.

$form['field_your_textarea_machine_name']['widget']['#after_build'][] = '_allowed_formats_remove_textarea_help';

Permissions

I have a few roles in my application, so I thought it would be better to control this functionality with a permission as opposed to explicitly stating the roles in the .module file.

.module file

$user = Drupal\user\Entity\User::load(\Drupal::currentUser()->id());

if (!$user->hasPermission('hide text formats and about text formats')) {

.permissions.yml

'hide text formats and about text formats':
  title: 'Hide text formats, "About text formats" and the surrounding box'

Sources

Issue d8 on d.o.
Thread on d.o. for solution in d6 and d7
Simplify module