/**
 * Removes Olark chat from non English pages.
 * @param $variables
 */
function yourtheme_preprocess_html(&$variables) {
  $language = \Drupal::languageManager()->getCurrentLanguage()->getId();
  if ($language <>'en' && isset($variables['page_bottom']['olark'])) {
    unset($variables['page_bottom']['olark']);
  }
}