For a current listing click on Revise Your Item, top left of listing, and untick the auto relist option near the bottom, above submit. But that may depend on how you originally listed it.
If it does relist you can end it early via the dropdown menu next to the item on your selling page. And relist with corrections.
For future listings you can cancel the relist option during the listing process before you submit. It's under pricing options on the far right.
