Use the Properties view to unsubscribe  from an alert.
    
- In the Perspective Resources view, select a resource and select 
                
 
- Select Alerts.
 
- Select an alert instance.
 
- In the Subscriptions tab, select the alert subscription and click  Drop.
 When you drop a regular subscription, any escalation subscription is also dropped. However, dropping an escalation does not affect the regular subscription.
 
- Click Yes to confirm the deletion.