You can use the same way to deploy a service with adding a new service. That is by configuring two XML files, the WidgetCatalog.xml file and the Service.xml file.
You can remove a service by removing the target node from the Service.xml file.
An end-user can subscribe a service by clicking the service from the service tree and then saving the Workplace. In this way the service is there next time the user logs in the Web 2.0 On-Demand Workplace.
If the user is no longer interested in certain service, he or she can unsubscribe it by closing the widget and saving the Workplace.