Delete Selected TreeNode from Xml C#

I am working on Winform using C#, i have populated Treeview from XML and need to Delete the treeview Selected Node ( Run time). Delete Event:

                TreeNode node = treeView1.SelectedNode;
                if (treeView1.SelectedNode != null)
                {
                    if (treeView1.SelectedNode.Parent == null)
                        treeView1.SelectedNode.Remove();
                    else if (treeView1.SelectedNode.Parent.Nodes.Count == 1)
                        treeView1.SelectedNode.Parent.Remove();
                    else
                        treeView1.SelectedNode.Remove();
                }

                XDocument doc = XDocument.Load("menu.xml");

                var xElement = (from q in doc.Elements("root")
                                where q.Attribute("quick").Value == node.Tag.ToString()
                                select q);
                foreach (var a in xElement) 
                    a.Remove();
                doc.Save("menu.xml");

     Where my XML file is:
        <?xml version="1.0" encoding="utf-8"?>
          <root>
         <quick title="1st Node" />
         </root>

Please help me.