Unsubscribing a Portal Event Using a Code Snippet 
You have created the views and their corresponding action handlers.
For more information, see Creating a View
For more information, see Creating an Action
In the Web Dynpro perspective, choose
In the Web Dynpro Explorer, select the required view.
Choose using the secondary mouse button.
Drag the UnSubscribe from a Portal Event snippet and drop it in the suitable user code area of the Java editor.
In the Insert Snippet: Unsubscribe to Portal Event dialog box, enter the necessary details such as Namespace, Name, and Handler Action and choose Insert.