First off, if you use chalk, wash it immediately after your training session.
Got to Walgreen’s or the like, and buy a pumice stone, a callus shaver (looks like a rasp), and a tin of Bag Balm
Use the pumice stone after a shower. When the skin is dry, use the callus shaver to clean up any dead skin that’s left. Lather your hands in Bag Balm before bed.
Never tore a callus using this method