How do I edit or remove a discount for a specific group of vehicles?

Answer:

Once you open the Remora Administrative Portal and select Automatic Pricing under the Inventory Mods tab (see how to access automatic pricing), any existing discounts appear beneath the heading of Current Discounts (pictured below).

You can either edit the discount percentage directly in the corresponding field or remove the discount entirely by clicking the red circle with an image of a trash can in it (previewed below).