$re = '%<img [^>]*?src=["\']data:image/svg\+xml[^>]+>%';
$str = '<div>
<img class="bumbum"><img src="data:image/svg+xml,%3Csvg xmlns="http://www.w3.org/2000/svg" width="960" height="640"%3E%3C/svg%3E" />
</div>';
$subst = "";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php