beat (something) out of (someone or something)
1. To aggressively get something (often information) from someone, either through interrogation or physical violence. Let me do the questioning—I'll beat the truth out of that witness. Luckily, a teacher came along before the bully could beat my lunch money out of me.
2. To repeatedly strike an object to remove something from it, usually in an attempt to clean it. I tried beating the dust out of that rug, to no avail.