名前空間を削除します。
if(sessionScope.ns != null) {
var ns = sessionScope.ns;
var p = requestScope.prefix;
if(ns.getNamespaceURI(p) != null) {
ns.remove(p);
requestScope.msg = "Namespace " + p + " removed";
} else {
requestScope.msg = "No namespace " + p;
}
} else {
requestScope.msg = "No namespaces";
}