There are a few treatments for calluses that work really well. Soaking the entire foot in warm soapy water and using a safety pedicure razor is the best treatment. Never push down on the tool, instead just run it across the callus until it's gone. This treatment is painless.
Another good option is corn and callus removing pads. The set comes with a sticker that has a type of callus remover on it. Put the sticker directly on the callus, and cover it with the flesh toned padded sticker. This treatment can take up to a week to remove a large callus.