When one diets, they lose some muscle mass. So, if you really wanted to lose weight, but still reduce the size of your calves- try this:
-Do all upper body exercises, ab exercises.
-No running. No leg exercises at all, except for inner thigh exercises.
-Have a fantastic food diet- low protein. (Muscles are fed by protein)
-Reduce your walking so that your muscle atrophy and become smaller. But make up for it by doing other exercises.
You can do it another way. Go on a regular diet, lose all the weight, then focus on your calves by cutting the protein, exercise on upper body and maintain your weight.
The only way to shrink a muscle is to not use it and not to feed it well. I have big muscular calves too, and they have reduced in size since I lost 20 pounds- even though all of it is muscle and even though I have exercised a lot. Maybe it's becoming more lean (stronger inside, but shrinking in size) I don't know if this would be true in your case.
Have you ever been thin and still have large calves?
Cheers,
George