- preg_replace: documentation ( source)
<?php
$_content = 'ho <div xmlns="http://www.w3.org/1999/xhtml" class="post_source_linkbar" xml:base="http://www.occuworld.org/feed">
<img src="https://fbcdn-profile-a.akamaihd.net/hprofile-ak-xap1/t5.0-1/373372_116415985219759_2395520276794396924_n.jpg" class="post_source_logo" /><img src="http://www.google.com/s2/favicons?domain=https%3A%2F%2Fwww.facebook.com%2F" title="I Acknowledge Apartheid Exists\'s Facebook Wall" class="post_source_icon" />Source</div> there';
echo preg_replace('/<div^[>]*class\=\"post_source_linkbar\"^[>]*>(.*?)<\/div>/i', '', $_content);