C#

string RemoveComments(string sDoc) {
      XmlDocument xDoc = new XmlDocument();
      xDoc.PreserveWhitespace = false;

      xDoc.LoadXml(sDoc);						// this will throw an exception if invalid XML

      XPathNavigator nav = xDoc.CreateNavigator();
      while (nav.MoveToNext(XPathNodeType.Comment)) {
        nav.DeleteSelf();
      } 

      StringWriter sw = new StringWriter();
      XmlTextWriter xtw = new XmlTextWriter(sw);
      xtw.IndentChar = ' ';
      xtw.Indentation = 2;
      xtw.Formatting = Formatting.Indented;

      xDoc.WriteContentTo(xtw);
      xtw.Close();
      sw.Close();
      return sw.ToString();
    }

StreamReader sr = new StreamReader("myOldFile.xml");<br />
            StreamWriter sw = new StreamWriter("myNewFile.xml");<br />
<br />
            string theText = sr.ReadToEnd();<br />
            sr.Close();<br />
<br />
            theText = theText.Replace("<!--", "");<br />
            theText = theText.Replace("-->", "");<br />
<br />
            sw.Write(theText);<br />
            sw.Close();