1) Decarbonise 2) Decarburise 3) Decarburize 4) Decoke 5) Remove 6) Remove carbon from 7) Take 8) Take away 9) To decoke 10) Withdraw 
• (v. t.) To deprive of carbon; as, to decarbonize steel; to decarbonize the blood.
De·car'bon·ize transitive verb [ imperfect & past participle Decarbonized ; present participle & verbal noun Decarbonizing .] To deprive of carbon; as, to decarbonize steel; to decarbonize the blood. Decarbonized iron...
to remove carbon build-up on piston, combustion chamber, and other parts.
[v] - remove carbon from (an engine)
decarbonise verb remove carbon from (an engine)
decarburize.