I wish I had the wonder exercise for you but you can’t spot target fat loss. You body burns your excess stores of body fat how it wants to and this is determined by your body type and genetics. Exercising your abs will build muscle and improve your body shape in that area but it has nothing to do with burning fat.
Creating a calorie deficit is the only way to reduce your body fat and this means decreasing your calories intake, increasing your calorie output or both. You have to create a calorie deficit over a prolonged period of time and aim for a realistic weight loss of around 2lb a week, anymore that this and you are moving towards crash dieting and this leads to a whole range of other issues that will hinder you losing your belly long term.
It is so much more than just eating less and doing a bit of exercise it means changing your lifestyle, daily habits and emotional links you have with food. It takes time, hard work and patience. But the good news is you can do it with the right tools and guidance, if you keep at it you will see the results.