I have an XML document that looks like this:
To remove the namespace completely, you'll need to use Regular Expressions (RegEx). For example:
$feed = file_get_contents("http://www.sitepoint.com/recent.rdf");
$feed = preg_replace("/<.*(xmlns *= *[\"'].[^\"']*[\"']).[^>]*>/i", "", $feed); // This removes ALL default namespaces.
$xml_feed = simplexml_load_string($feed);
Then you've stripped any xml namespaces before you load the XML (be careful with the regex through, because if you have any fields with something like:
cool. ]]>
Then it will strip the xmlns from inside the CDATA which may lead to unexpected results.