CAS Tools is for clothing, hair, and accessories, not skin tones. Skininator works with skintones. I've never looked at hiding game skintones and don't know how to do it or if it's possible. What you could do is clone them and replace the textures with custom textures.
I'll take a closer look tomorrow and get back to you if there's some clever way to hide them.
Please do not PM me with mod, tutorial, or general modding questions or problems; post them in the thread for the mod or tutorial or post them in the appropriate forum.
You could try cloning default replacements of the EA skintones and removing all the property tags. Since the Occult property determines if the skintone shows up in CAS for the specified occult type (human, alien, etc) it should hide the tone in CAS.