Normally, the Delete option only deletes one level. Deep Delete allows child business components and their respective child business components to be deleted automatically when selecting the Delete option. This feature allows multiple levels to be deleted like a cascade delete.
Create a multivalue field in the parent business component, using the multivalue link. This field is usually not displayed on the screen but needs to be present on the business component.
This is analogous to the Deep Copy user property. Use Deep Delete to do a deep cascade delete. Typically, use Deep Copy and Deep Delete together.