<?php
$html =  file_get_contents('http://www.stackoverflow.com/');
$dom = new DOMDocument;                 // init new DOMDocument
$dom->loadHTML($html);                  // load HTML into it
$xpath = new DOMXPath($dom);            // create a new XPath
$nodes = $xpath->query('//a[@href]');   // Find elements with a style attribute
foreach($nodes as $node) {              // Iterate over found elements
    $node->removeAttribute('href');    // Remove style attribute
}
echo $dom->saveHTML();
?>