Cancel Method
This will cancel another entity's subscription to this entity's presence.
Syntax
[VB.NET] Public Sub Cancel(ByVal JabberId As String)
[C#] public void Cancel(string jabberId);
Remarks
If for any reason the user should want to undo a previously granted subscription, this can be achieved through the Cancel method. The method will unsubscribe the target from this user's presence, thus preventing the target from seeing this user in the future.