As has been said, diet is the only thing that's really gonna do it.
That being said, you can work on exercises to build up your lower abs so they're stronger underneath and pushing out more, too (e.g. hanging leg raises, reverse crunches, full range cable crunches). And once you're really down to the last bit of fat (already around that single digit bf% point), you could add in a topical fat-burner, too. You could toss in some Thiomucase and even add in some clen with it, if that's something you're interested in.