Remove WordPress nav menu item if asociated page is trashed

delete.php

<?php
  add_action( 'publish_to_trash', 'klausk_delete_menu_item' );
  function klausk_delete_menu_item($post) {
    // tik puslapiams
    if( $post->post_type !== 'page' )
      return;
    // jei tema nepalaiko meniu - nieko daryti nereikia
    if ( ! current_theme_supports( 'menus' ) ) { return; }
    // trinamas meniu punktas
    _wp_delete_post_menu_item($post->ID);
  }
?>