In the flow chart model elements can be deleted by selecting them and then either:
selecting Delete on Home tab of the ribbon or
pressing Del key
Deleting an organization item in the flow chart deletes only the organization row from this process level. To delete the organization item completely, open the organization item dialog and click the Delete button or delete the organization item from the navigator window.
The subprocess start and end triangles cannot be deleted. They are automatically created with the subprocess they belong to. Deleting a subprocess also deletes all process steps, connectors and groups that are in it.
Deleting a process step automatically deletes all connected groups and all connectors that will not be connected to any process steps after the deletion. Deleting a process step, flow or a group also deletes all measure values connected to it.