callus are not always harmful, and they are the reaction of the skin to repeated friction. Vinegar is an ineffective remedy for corns removal, because they are weak acids. Salicylic acid solution is effective and safe if used properly, just put on top (not on normal skin border) of the corn and it will be removed. But corns in diabetics should be consulted first to the doctor to prevent complications.
Yes you can remove corns with vinegar. Soak some bread crumbs in vinegar for 30 minutes to make a paste. Before going to bed take a warm bath to soften the corn and apply the paste on the corn and let it stay overnight. A plastered bandage can hold the paste securely so it won't get dislodged during sleep. The morning after, the corn will be soft enough to peel off.