poop as much as you can and frequently
Try using a knife. Hurts like hell, and you risk a deadly infection or bleeding to death if you're not careful. The other way takes a lot longer and isn't as comfortable, but you can try not eating so much food.
The best way to lose the fat is to transform it to muscle. It will be firmer and flatter if you gain a bit of muscle as you lose the fat. If you don't you will end up with flab, and you won't enjoy that.
How long did it take to gain the belly fat?
There was a reason for asking about how long it took to gain it. It takes longer to lose it than it does to gain it.. It is a lot harder to get rid of than it is to gain the weight. It takes determination and a good healthy diet and exercise. It won't be easy. It isn't easy for anyone. I'm sorry. If anyone tells you there is a quick way to lose the weight, you can be sure you will gain it all back and an extra 5 pounds besides. I know, because I did it. I tried every quick weight loss scheme there was, but they were impossible to maintain and when I went back to eating my normal foods, I gained back all I had lost and 5 extra pounds. Several times this happened, until I weighed 35 pounds more than I did, when I decided to lose the weight.
Sleep for 3 weeks and occasionally wake up to drink water (caution: your organs might shut down but it'll get u a flat stomach!)
Oh and btw at your age it's almost impossible to get a flat stomach ;-)
You need to generally lose fat on your entire body. Spot-reduction is a myth.
Don't eat anything anytime if you really want to work on stomach..
Go for Cardio & Abs workout.
Run two hours a day.
Its not easy.