Reducing only thighs from the body is not possible,you have to reduce from the overall body.The aerobic exercises and healthy diet help you to burn calories while strength training helps you to shape up the muscles and also increase your lean body mass.Aerobic exercises can be done by walking,running,swimming,skating,trampoline etc.Strength training for thighs includes leg curls,leg press,donkey kicks,squats with variations can be performed.