You can always remove or re-order photos in the Photo Manager under "Edit Listing." Just select the image(s) you want to delete, click the pencil button in the upper-left corner, and select "Delete this photo." Of course, you'll still need to have other photos in their place for your listing to be viable.
You won't get a refund for doing this, though. Airbnb's photography service was an appealing option back when they offered it for free, but now that they charge for it I don't recommend it. Better if you can hire a freelance photographer whose work you can see before booking them.