Answer:
U need to solve the root of the problem
Step-by-step explanation:
Why is that person a bully? Maybe it's a terrible family life, maybe it's because it lacked attention growing up and thinks being a bully is the only way, maybe the person itself is bullied, or maybe the person just wants to fill their ego
Honestly there's a lot of reason and there's no one solution, we can only try to solve the root of their problem, though it may not change them as changing a person personality is very hard.
also i feel like i need to add that i don't support bullies i think they're shi.tty people but there are reasons for why someone is terrible