<?php

$html = <<<DATA
<html>
<body>
<div id="r1">
 <a href="link">Link</a>
</div>
<div id="r2">
 <a href="link">Link 2015-09-12</a>
</div>
</body>
</html>
DATA;

$dom = new DOMDocument;
$dom->loadHTML($html);
$myVariable = "2015-09-12";

$xpath = new DOMXPath($dom);
$divs = $xpath->query("//div[contains(.,'$myVariable')]");

foreach($divs as $div) { 
   $div->parentNode->removeChild($div);
}

echo $dom->saveHTML();