[ns] how to stop a particular node?

[kavan sheth]

Hi all,
 currently I am working on address allocation in MANET. for that I was
implementing an addressing agent MANETconf, which works above routing
protocol. As part of simulation scenario I need to simulate departure
of node so a node does not participate in packet forwarding. I tried
$node_(i) reset but it doesn't work.
can any one suggest me how to stop a node(or disable routing agent on a node)?