Remove nodes from treeview control on client side

[Oren]

Hi,
I have a treeview control on my page. I'm having no problems adding nodes to
the control with my Jscript on the client-side, but when I want to remove a
node from the treeview it shouts "object doesn't support this property or
method".
I'm using the following code to remove the node:

var itemNode = Treeview1.getTreeNode(itemIndex);
itemNode.Remove();

Thank you very much