Depending on location and depth an over the counter pumice stone may suffice your needs. Otherwise you should be evaluated and treated by a Board Certified Podiatric Surgeon.

Calluses are 'pressure' or 'mechanical' lesions. You can use Keratolytic creams, like Urea or Ammonium Lactate creams to soften the skin and then use a pumice stone or callus file to remove some of the extra skin, which will help to keep them at bay. Alternatively, you may see a foot and ankle specialist, and you may be able to use orthotics (arch supports) or possibly may need surgery to change the mechanics and pressure points on your feet.

Calluses will develop due to excessive pressure in an area not designed to have that pressure. I recommend you see a foot and ankle surgeon (podiatrist) to discuss the cause and appropriate treatment options