You can’t. Not without dying, anyway. Professional bodybuilders who spend their entire waking lives honing and shaping their bodies can get down to perhaps 2 or 3 percent body fat with monumental amounts of constant effort. The only way you’ll get rid of all your body fat is to starve yourself to death.
If your question is more about general weight-loss, try eating whole foods. Insulin encourages the body to store fat. Anything which causes spikes of insulin should be avoided. The Glycemic Index measures the relative amounts of insulin different foods will cause your body to release. If you want to lose weight without altering the amount you eat, eat low-GI foods. Whole foods generally have a much lower GI than processed foods. Contrary to popular belief, not all calories are equal. Exactly the same number of calories in high-GI foods will cause you to gain more weight than low-GI foods.
Long-term weightloss is so difficult that statistically it’s close to zero. Bariatric specialists believe today that surgical intervention is the only long-term solution for obesity. If you expect to take weight off for any appreciable period of time, you’re going to completely change your relationship with food. It can’t be something special you do; if it’s not something you can maintain for the rest of your life, it’s not going to work.