If you add stages for a case type, the system automatically creates an instance of pyStartCase in the case type and adds it to the Starting Process list. This flow is necessary to initialize the first stage and stage processing. You can configure work object creation settings such as making a case a temporary object, looking for assignments to create, and so on from the pyStartCase form. If there are stages defined for the case type and you remove the flow from the list, the system automatically adds it back when you to save the case type record.
If you remove all the stages from the Stages and Processes tab, pyStartCase remains in the list but is not implemented.