Forget about it. I was using the white Noot as my favorite case. However, I would find it discolored at the edges within a week or so. I tried everything from nail polish remover, to bleach to polident and nothing took out the staining. I even put them through the dishwasher. Some Internet research will tell you that TPU absorbs stains very easily but won't release them. Just the nature of the material. I would love to hear someone else come through with a miracle way to clean the Noot.