C#删除xml中某个节点的子节点方法

            if (File.Exists(xmlFilePath))
            {
                XmlDocument xmlDoc = new XmlDocument();
                xmlDoc.Load(xmlFilePath);
                XmlNodeList nlist = xmlDoc.SelectNodes("/configuration/appSettings/add");//获取了所有叫add的节点，而不是父节点的所有子节点
                XmlNode appsetting = xmlDoc.SelectSingleNode("/configuration/appSettings");
                //Delete related
                foreach (XmlNode xn in nlist)
                {

                    textbx_process.AppendText((xn.Attributes["key"].Value).ToString() + "\r\n");

                    if (xn.Attributes["key"].Value == "Azure1")
                    {
                        //xmlDoc.SelectSingleNode("/configuration/appSettings").RemoveChild(xn);
                        appsetting.RemoveChild(xn);
                    }
                    if (xn.Attributes["key"].Value == "Azure2")
                    {
                        //xmlDoc.SelectSingleNode("/configuration/appSettings").RemoveChild(xn);
                        appsetting.RemoveChild(xn);
                    }
                    if (xn.Attributes["key"].Value == "Azure3")
                    {
                        //xmlDoc.SelectSingleNode("/configuration/appSettings").RemoveChild(xn);
                        appsetting.RemoveChild(xn);
                    }
                }

注意不宜采用注释掉的语句，否则删除不成功