From the main hillslope picture double click on the bottom slope layer and the desired soil section. You can also select the soil section and then right-click to display the menu and then click View/Edit.
Click the SaveAs button and give the soil a new name.
Click the Delete button and then click OK when asked to confirm the delete operation. The current soil can not be deleted, a different soil must first be imported into the soil section and the soil editor displayed so the unused soil can be selected and then deleted.