1. To criticize, upbraid, or condemn someone or something severely or thoroughly. A: "Have you heard anything about this movie we're about to see?" B: "Well, one reviewer tore it to pieces, but I still think it's going to be great." I hear John's bosses tore him to pieces at his annual performance review.
2. To cause great damage, disorder, or ruin to someone or something. Enjoy the tranquility and order of your house now because soon, your kids will start tearing the place to pieces. Sarah's very first opponent in amateur boxing tore her to pieces, but that's how it goes for most novice fighters.