It would be absolutely amazing if we had the ability to edit t-shirt color availability. One of my very first uploads nearly 2 years ago was a design done in all black line art. On-screen it appeared that black would show well on some of the darker colored tees, but in reality, it does not. The design is available on both dark and light colors, in the beginning, only the lighter color was selling, but over time more of the darker has sold and it tends to get returned often with a few reviews saying the design can hardly be seen. It's still one of my best consistent sellers so I don't want to delete the listing and lose the ranking and reviews in order to upload with a new selection of t-shirt colors that I know work well. Fortunately, one reviewer said the design itself was solid, but to order it on a lighter color so it can be seen... Still, it would be absolutely amazing if we had the power to correct that ourselves, without removing the listing.
On that note.. it would be equally amazing if we had the ability to do a design re-submission that fixed any small inconsistencies caught after the upload... Even if that required a separate review process on amazons end for whatever reason like maybe you need to verify that it was only a minor change and the design itself is still the same. It would be interesting to know why design re-submissions and color changes are not accessible to us. It doesn't make sense to me why not.. nothing is printed until ordered.