More cardio with the same amount of food. It's as simple as burning more calories than taking in.
Mind you, every human being has abs. It just depends on how much fat is covering them. So how do you get rid of fat? You burn calories. How do your burn calories? You do cardio.
Also train your abs in the gym. Your abs are a very resilient muscle. If you want abs to be pronounced, deep, and cut, you need to train them heavy. Your abs take punishment from your daily activities every day so it is very difficult to make them grow. Do these two exercises...
1. Med-Heavy cable crunches.
2. Med-Heavy Leg Lifts.
I do not recommend doing side crunches that hit the oblique muscles as they widen your stomach form the front view.
Here are my abs in competition and modeling time:
My years of competitive bodybuilding and modeling.