1) Achromatise 2) Alter 3) Change 4) Deprive or free of color 5) Modify 6) Remove color from 7) To deprive of colour 8) To make achromatic Found on https://www.crosswordclues.com/clue/achromatize
A·chro'ma·tize transitive verb [ imperfect & past participle Achromatized ; present participle & verbal noun Achromatizing ] [ Greek 'a priv. + ... color.] To deprive of color; to make achromatic. Found on http://www.encyclo.co.uk/webster/A/19