Detrahere and subtrahere are both fine, but I would actually go with subducere, which is used in mathematical reckoning:
- Rationem, to draw up, cast up, reckon, compute, calculate, or balance an account (by subtracting one set of items from another; class.; “esp. freq. in Cic.): subduxi ratiunculam, Quantum aeris mihi sit, quantumque alieni siet,” Plaut. Curc. 3, 1; cf.: “intus subducam ratiunculam, quantillum argenti mi siet,” id. Capt. 1, 2, 89: “subducamus summam,” Cic. Att. 5, 21, 11; cf.: “assidunt, subducunt: ad numum convenit,” id. ib. 5, 21, 12.—
It also carries all the meaning of subtrahere in it, but the added calculation makes it a good contender.
That said, if you're just aiming at an audience that isn't particularly familiar with Latin, you could go the Renaissance/Neo-Latin route and use subtrahere (whence subtractio).
Sebastian has a straightforward rendition (Ars est subducere), but I'll offer another:
Omnis ars ex subducendo.
All art from subtraction.
It's ambiguous a bit, but you did ask for brief. I think adding the omnis really emphasizes the overall importance of subtraction. All of art, not just some abstract portion of it, is affected by/made up of/etc. subtraction.