Can a Darwin's Tubercle Be Removed Without a Scar Even when It's on an Uncurled Helix?

The answer is no, surgery cannot be performed without a scar.  The goal is that the deformity be corrected and the scar is camouflaged  enough to avoid detection.  This always includes the thoughtful placement of incisions, which can be completely out of site, hidden along shadows or natural curves, and performed meticulously enough to achieve excellent healing.  For a Darwyn's tubercle the incision would be made on the posterior surface of the ear and the tubercle excised after the skin was elevated anteriorly over the tubercle.  The skin on the posterior surface of the ear almost always heals favorably.