Too much cardiovascular exercises can build up your calf muscles. In order to reduce them, do exercises which do not include any running, cycling and exercises which involve a lot of leg exercises. In case you do some leg exercises, make sure you lift low weights. Swimming is a good way of reducing the calf muscles as more of the upper body muscles are toned compared to the lower body. Actually, the calf muscles are very difficult to build up and let go off. The best way to reduce calf muscles would be to not walk and run much, but by doing this it may also increase your weight.