May I ban my younger brother Fortnite?

My brother (14) has been playing a lot lately. So at the 6 hours a day. May I ban him from continuing?

Your parents are responsible for that

Forbidding is perhaps the wrong word. Search the word with him. Is he trying to distract himself with that? Does he have quarrels with friends? I would rather try to find a compromise with him, like "play two hours and then we can do something together". It's definitely better than banning things that will be even more appealing.

No.

You're most likely not legal for your brother. So this is the job of your parents. If you really want to do something, you can appeal to them. But even that I would rather leave.