Use to delete a decommissioned component:
      Decommision the component that you intend to delete.
- 
            Using Ambari Web, browse the Hosts
               page.
         
- 
            Find and click the FQDN of the host on which the component resides.
         
- 
            In Components, find a decommissioned component.
         
- 
            If the component status is Started, stop it.
            A decommissioned slave component may restart in the decommissioned state. 
- 
            Click Delete from the Action
               drop-down menu.
            Deleting a slave component, such as a DataNode does not automatically inform a
               master component, such as a NameNode, to remove the slave component from its
               exclusion list. Adding a deleted slave component back into the cluster presents the
               following issue: The added slave remains decommissioned from the master's
               perspective. Restart the master component, as a work-around.
- 
            Restart services.
         
Ambari recognizes and monitors only the remaining
         components.