Hiding or Changing the List Heading
The default heading of the list (“Pages”) of Pages generated by wp_list_pages can be hidden by passing a null or empty value to the title_li parameter. The following example displays no heading text above the list.
<ul>
<?php wp_list_pages('title_li='); ?>
</ul>
http://codex.ww.wp.xz.cn/Template_Tags/wp_list_pages
