To get rid of belly fat without losing your butt and thickish legs, eat low fat foods. Eat small meals at regular intervals throughout the day. Do a combination of cardio and stretching exercises that are aimed at building strength and burning calories. It is also advisable that you stop drinking sugary drinks and go for fresh fruits and juice instead.
You can not choose where to lose fat .. Your brain does not distinguish unwanted butt fat from tummy fat .. To the metabolism system fat is fat. You CAN however tighten the muscles in those areas which will offer a better appearance.