Remove xmlns and select signle node, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Xml;
using System.Xml.Linq;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //Your code goes here
            //Console.WriteLine(xdoc.DocumentElement);
            XmlDocument xdoc = new XmlDocument();
            var sxml = "<?xml version=\"1.0\" encoding=\"utf-8\"?><CalcolaSimulazioneOut><ID_Pratica xmlns=\"http://www.bnl.it/peqc/webservices\">12345</ID_Pratica><Tan xmlns=\"http://www.bnl.it/peqc/webservices\">7.04</Tan><Montante xmlns=\"http://www.bnl.it/peqc/webservices\">9720</Montante><Interessi xmlns=\"http://www.bnl.it/peqc/webservices\">981.49</Interessi><Finanziato xmlns=\"http://www.bnl.it/peqc/webservices\">8738.51</Finanziato><Commissioni xmlns=\"http://www.bnl.it/peqc/webservices\">245.80</Commissioni><SpeseIstruttorie xmlns=\"http://www.bnl.it/peqc/webservices\">100</SpeseIstruttorie><SpeseDistribuzione xmlns=\"http://www.bnl.it/peqc/webservices\">45.80</SpeseDistribuzione><ImpostaDiBollo xmlns=\"http://www.bnl.it/peqc/webservices\">0</ImpostaDiBollo><SpeseDiIncasso xmlns=\"http://www.bnl.it/peqc/webservices\">0</SpeseDiIncasso><FondoRischiInpdap xmlns=\"http://www.bnl.it/peqc/webservices\">0</FondoRischiInpdap><ImportoDaErogare xmlns=\"http://www.bnl.it/peqc/webservices\">8492.71</ImportoDaErogare><Taeg xmlns=\"http://www.bnl.it/peqc/webservices\">8.50</Taeg></CalcolaSimulazioneOut>";
            
            xdoc = RemoveXmlns(sxml);
             
            Console.WriteLine(xdoc.SelectSingleNode("CalcolaSimulazioneOut/ID_Pratica").InnerText);
            
        }
        
        public static XmlDocument RemoveXmlns(String xml)
        {
            XDocument d = XDocument.Parse(xml);
            d.Root.Descendants().Attributes().Where(x => x.IsNamespaceDeclaration).Remove();

foreach (var elem in d.Descendants())
                elem.Name = elem.Name.LocalName;

var xmlDocument = new XmlDocument();
            xmlDocument.Load(d.CreateReader());

return xmlDocument;
        }
    }
}

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Compilation time: 0,16 sec, absolute running time: 0,22 sec, cpu time: 0,2 sec, average memory usage: 18 Mb, average nr of threads: 4