to remove root from tree view controls

Start with mark-up similar to the following:

<asp:treeview xmlns:asp="#unknown">
    ID="tvRPM"
    runat="server"
    EnableClientScript="true"
    ExpandDepth="0"
    PopulateNodesFromClient="true"
    ShowLines="true"
    OnTreeNodePopulate="PopulateNode"/>
</asp:treeview>

You would then populate the parent from the OnLoad event and populate children from the event you attach to the OnTreeNodePopulate event: in the case above I have called my method, rather unimaginatively, 'PopulateNode'. It has this signature:

protected void PopulateNode(Object sender, TreeNodeEventArgs e)
{
	// Code to populate the child nodes...
}

That should get you started: you'll need to do some further research but that should be fun.