Have you thought about the reasons WHY it didn't sell?
What's the price?
Is it in the right sub genre?
What tags has it got?
Is it easy for the reader to find?
Does it have a good cover?
Does it have a good description?
I would have a look at those things and see if you can find the reasons why it didn't sell, rather than just write it off.
This. Self-promo can help in some cases, but a lack of it is not necessarily the cause of poor sales.
Also, how long was it for sale? "Normal" is months to ramp up sales.
And further also, it's just
one story. We'll assume that means short story. Typical sales are 0-5 copies of a short story per month, and some are 0 for many months straight so you tend to need a decent inventory of short stories available.
Putting up a single short story and expecting more is undue expectations on the part of the writer/publisher.
The same can be said of the more traditional short story publication. It's like writing one story, and sending it to one venue and expecting it to sell. That's not a reasonable expectation.
The typical writer will need to write dozens of stories and make multiple submissions of each before getting a sale. (My ratio is actually above average for a nobody, selling about 1 in 10 but that means 100+ rejections for the 10+ published stories factoring in a few acceptances that never saw print. Many authors collect 100 rejections before they sell
anything.)
So the traditional method of selling short stories isn't typically any easier or faster than self-publishing.
Wow, that's a long aside.
Publication does not equal sales. So it's been "published". However, you'd probably never have an issue with sort of forgetting it ever happened first because odds are the story won't sell traditionally anyway and further if you get lucky and sell it odds are the publisher will never find out it was previously published if there were no sales and no remaining trace that it was ever previously available (like copies sent to review sites, etc.) But I wouldn't recommend trying to sneak it through the system. I'd write another story and submit that to traditional publishers and republish the current one on KDP (if you're still satisfied that the story itself and the packaging--cover, blurb, etc--are good.)