function stripXMLNamespaces(xml:XML):XML
{
    var s:String = xml.toString();
    var pattern1:RegExp = /\s*xmlns[^\'\"]*=[\'\"][^\'\"]*[\'\"]/gi;
    s = s.replace(pattern1, "");
    var pattern2:RegExp = /<[\/]{0,1}(\w+:).*?>/i;
    while(pattern2.test(s)) {
        s = s.replace(pattern2.exec(s)[1], "");
    }
    return XML(s);
}

http://enva.to/e4ig6z

<p>Loading XML, specifically from 3rd party sources can sometimes prove problematic when the XML makes use of namespaces. This snippet will take an XML object and strip all namespace declarations and prefixes. This snippet leaves the input XML unchanged and returns a new XML object.</p>

Strip XML Namespaces

ActionScript 3