//Create our own namespaces for the output
XmlSerializerNamespaces ns = new XmlSerializerNamespaces();
//Add an empty namespace and empty value
ns.Add("", "");
//Create the serializer
XmlSerializer slz = new XmlSerializer(someType);
//Serialize the object with our own namespaces (notice the overload)
slz.Serialize(myXmlTextWriter, someObject, ns)