Sample code for StackOverflow answer here: http://stackoverflow.com/questions/987135/how-to-remove-all-namespaces-from-xml-with-c/7238007#7238007

RemoveXmlNamespace.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml.Linq;
using System.Threading.Tasks;

namespace RemoveXmlNamespaceApp
{
    class Program
    {
        // my SO answer here: http://stackoverflow.com/questions/987135/how-to-remove-all-namespaces-from-xml-with-c/7238007#7238007

        public static XElement RemoveAllNamespaces(XElement e)
        {
            return new XElement(e.Name.LocalName,
               (from n in e.Nodes()
                select ((n is XElement) ? RemoveAllNamespaces(n as XElement) : n)),
               (e.HasAttributes) ? (from a in e.Attributes() 
                                    where (!a.IsNamespaceDeclaration)
                                    select new XAttribute(a.Name.LocalName, a.Value)) : null);
        }
        static void Main(string[] args)
        {
            
            var doc = XElement.Parse(@"<list:employeeList xmlns:list=""urn:corp:list"" xmlns:emp=""urn:corp:emp"" xmlns:sec=""urn:corp:sec"">
                                        <list:personList>
                                          <emp:empID>E0000001</emp:empID>
                                            <sec:name>Sales</sec:name>
                                            <emp:name emp:favoritecolor=""blue"">John Smith</emp:name>
                                          </list:personList>
                                          <list:mixedmode>hello<emp:name>Smith</emp:name></list:mixedmode>
                                        </list:employeeList>");

            var new_doc = RemoveAllNamespaces(doc);

            
        }
    }
}