Removes FIELD_NAME from ALL content types on DRUPAL8

mymodule.install

/**
 * Removes FIELD_NAME from ALL content types.
 */
function MYMODULE_update_8001(&$sandbox) {
  $contentTypes = [
    'blog_post',
    'case_study',
    'industry',
    'video',
    'whitepaper'
  ];
  $entityManager = \Drupal::service('entity.manager');
  foreach ($contentTypes as $contentType) {
    $fields = $entityManager->getFieldDefinitions('node', $contentType);
    if (!empty($fields['FIELD_NAME'])) {
      $field = $fields['FIELD_NAME'];
      $field->delete();
    }
  }
}