Best yet easiest way to lose stomach fat fast?

I’m fourteen years old, and starting high school soon and I’ve noticed that I have a lot of extra fat in my stomach. I’m not saying that I’m fat myself, my legs are skinny and so is everything else, it’s just I have a big stomach from not eating too healthy.

What’s the best way to flatten my stomach? Tips and procedures please. Which are the best exercises and how many times should I do them each? What should I deprive myself of?