How to remove a term programmatically from entity reference field using entity browser on translation form?

Question

I have a content type "Articles", this is a multi-language site, by default the content is created in English, and then translated into Spanish. On new article in English, I set a title and a term for the "Category terms" field, this field is an "Entity Reference", and I'm using "Entity Browser" to show terms from a view (they are a lot of terms), when I create a translation from English to Spanish I need to remove any term related to "Category terms" field. I have tried a couple of ways, but this is not working for this field.

Here is the hook code that I'm using.

<?php

use Drupal\Core\Form\FormStateInterface;

/**
 * Implements hook_form_alter().
 */
function mymodule_form_alter(&$form, FormStateInterface $form_state, $form_id) {

  // Form state object double check.
  if (is_object($form_state) && method_exists($form_state, 'getStorage')) {

    $form_storage = $form_state->getStorage();

    // Temporal condition to avoid unexpected results while developing
    if ($form_id == 'node_articles_form') {

      // Check if form is a translation.
      if (isset($form_storage['content_translation'])) {

        // Hard coded test to override title - This works.
        $form['title']['widget'][0]['value']['#default_value'] = 'Forced title text translation';


        // Hard coded test to override Meta Search Terms - This doesn't work. Is not applyed
        $form['field_category_terms']['widget']['entity_browser']['#default_value'] = [];

        // Removing completely the field - This is not a solution, only for test.
        // unset($form['field_category_terms']);

        // Removing data from "Callback Object"
        $build_info = $form_state->getBuildInfo();
        // Getting the entity
        $entity = $build_info['callback_object']->getEntity();
        // Removing terms from entity
        $entity->field_category_terms = [];
        // Setting the entity
        $build_info['callback_object']->setEntity($entity);
        // setting a modified callback object to the $form_state
        $form_state->setBuildInfo($build_info);

        // Removing target_id default value.
        unset($form['field_category_terms']['widget']['target_id']['#default_value']);
      }
    }
  }
}

Answer 1

To remove them from the user interface, you would have to empty the items array of 'current'

$form['field_category_terms']['widget']['current']['items'] = [];

This would however only hide them in the user interface, to actually remove them you also have to NULL target_id

$form['field_category_terms']['widget']['target_id']['#default_value'] = '';

If the users are allowed to add new terms during the translation, you'd also need to make sure the emptying of the terms only are done initially, because if not, they would always appear empty since Entity Browser uses AJAX and change the form when you add a new term. Something like:

  if (!$form_state->isProcessingInput()) {
    $form['field_category_terms']['widget']['target_id']['#default_value'] = '';
    $form['field_category_terms']['widget']['current']['items'] = [];
  }