Remove „Private:“ from the titles of private WordPress pages

# add to functions.php of your theme
function the_title_trim($title) {
  $title = attribute_escape($title);
  $findthese = array( '#Protected:#', '#Private:#' );
  $replacewith = array( '', // What to replace "Protected:" with '' //What to replace "Private:" with );
  $title = preg_replace($findthese, $replacewith, $title);

  return $title;
}
add_filter('the_title', 'the_title_trim');