The color comes from a rearrangement of the metal matrix at the surface of the metal, which causes light of certain wavelengths to be reflected to the eye. To remove color from anodized titanium, you need to remove this thn layer of rearracnged molecules. I have never messed with titanium myself, so I am not sure how deep the color effect goes, but light sanding is what you need to do. Someone who has CR knife can probably tell you what grit to use, or are they sandblasted?