public partial class selectPOSReports : Form
    {
        XmlDocument doc = new XmlDocument();

        public selectPOSReports()
        {
            InitializeComponent();

            if (!File.Exists(@"C:UsersPublicMECposReportList.xml"))
            {
                Directory.CreateDirectory(@"C:UsersPublicMEC");
                doc.LoadXml("<?xml version="1.0" encoding="utf-8"?><Reports count="0"></Reports>");
                doc.Save(@"C:UsersPublicMECposReportList.xml");

            }
            else
            {
                doc.Load(@"C:UsersPublicMECposReportList.xml");
            }

            XmlNodeList excelReportList = doc.SelectNodes("//Workbook");

            foreach (XmlNode excelReport in excelReportList)
            {
                reportList.Items.Add(excelReport.InnerText);
            }
        }

        private void addButton_Click(object sender, EventArgs e)
        {
            int newIndex = 0;
            if ( selectReportDialog.ShowDialog() == DialogResult.OK ) {
                doc.Save(@"C:UsersPublicMECposReportList.xml");
                string fileName = selectReportDialog.FileName;
                string filePath = Path.GetPathRoot(fileName);
                XDocument xd = XDocument.Load(XmlReader.Create(@"C:UsersPublicMECposReportList.xml"));
                xd.Element("Reports").Add(
                    new XElement("Report", new XAttribute("id", newIndex),
                    new XElement("Workbook", fileName),
                    new XElement("Filepath", filePath)));
                xd.Save(@"C:UsersPublicMECposReportList.xml");
                reportList.Items.Add(fileName);
            }
        }

        private void removeButton_Click(object sender, EventArgs e)
        {
            DialogResult result = MessageBox.Show("Are you sure you want to remove " + reportList.SelectedItems.ToString() + " from the list?",
                            "Remove Excel Report",
                            MessageBoxButtons.YesNo,
                            MessageBoxIcon.Warning);

            if (result == DialogResult.Yes)
            {
                int index = reportList.SelectedIndex;
                string sindex = index.ToString();
                XmlNode deleteNode = doc.GetElementById(sindex);
                deleteNode.ParentNode.RemoveChild(deleteNode);
                doc.Save("posReportList.xml");
                reportList.Items.RemoveAt(index);
            }
        }
    }

<Reports count="1"><!--Count will be updated as items are added-->
    <Report id="1">
        <Workbook>SomeBook.xlsx</Workbook>
        <Filepath>C:/SomePath</FilePath>
    </Report>
</Reports>

doc.Save(@"C:UsersPublicMECposReportList.xml");

xd.Save(@"C:UsersPublicMECposReportList.xml");