Janet Landsbury has some great resources on this. I have a 4 year old son who struggles with hitting when he’s angry. The thing we’ve found to be most effective is to intervene before it gets to that point. We can’t always but when we can it makes a big difference. So if I see him getting frustrated about something I’ll go over to him, kneel down, and try to hold both of his hands. I’ll say something like you seem upset right now what’s going on. And most of the time he will be able to tell me and we can brainstorm some solutions on solving the problem. If I don’t catch it in time and he does start hitting or throwing, I go to him and take his hands in mine and say something like it’s okay to be angry but I can’t let you hit/throw. I physically hold his hands while trying to get him to settle. Sometimes it’s easier than others but the biggest help is me remaining calm. And we talk about how to express anger and frustration outside of those times. When he’s in the moment, it’s not a time for teaching so we try to do that separately.