private void DeleteStudent_Click(object sender, EventArgs e) { ProgressVisibleFalse(); ThemesVisibleFalse(); RegistrationVisibleFalse(); FiltrationVisibleFalse(); int k = listofStudents.SelectedIndex; if (k > -1) { listofStudents.Items.RemoveAt(k); XmlDocument xDoc = new XmlDocument(); xDoc.Load("users.xml"); XmlElement xRoot = xDoc.DocumentElement; XmlNode Del; Del = xRoot.ChildNodes[1]; XmlNodeList node = Del.ChildNodes; XmlNode a = node[k]; Del.RemoveChild(a); xDoc.Save("users.xml"); } }