Relieve pressure. Corns and callouses are representations of pressure areas on the skin. They will go away if you remove the source of pressure. Unfortunately, with deformities like hammertoes its hard to remove all pressure of shoes. When they develop despite change in footwear and are painful, the hammertoes or other bony prominences should be corrected surgically.
Lotion or surgery. . Corns and calluses occur because of pressure points. Surgery can fix this, but if you're not ready for that, trimming them down and regular use of lotion may soften them to the point they don't bother you. You can also try larger shoes that don't rub against the painful areas! offloading orthotics can also help: see your podiatrist for casting.