So we currently have a few suggestions to remove books/foods. See Cleansing Pools: Books & Foods and A way to delete food from pet&;s food list (or to unfeed food items) But it wouldn't give you your money back. That isn't exactly what you are proposing though but the title is misleading in that regard. If you could maybe rename it to Hide certain pets from item use.
There was talk of this when the whole item use menu was being talked of a revamp. I am on my phone right now so hard to find the old posts. However, I would say this is still probably on the radar down the line when we switch just because it is a quality of life change that has been requested quite a few times and there are many users with over 20 pets
Edit Feedback: Pet "limit" / farm So this is one of the ideas that was thrown around from Keith himself.