Unable to unsubscribe to an event

I have subscribed to Event "MessageUpdate" using event subscription , got a token . Now using this token i am trying to unsubscribe but getting following error :

url :https://cloudsquadsdev2.stage.lithium.com/restapi/vc/events/subscriptions/token/{msgToken}?restapi.session_key={session_key}

Response :

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<response status="error">
<error code="504">
<message>
Method &apos;post&apos; is not supported off of node &apos;event_subscription_manager.subscriptions.token.Param0&apos;.
</message>
</error>
</response>