My Toxic Friend

I have a friend who has made roughly around 10 accounts. He's constantly being toxic in game even after he's gotten multiple accounts to level 30. I try to help him by telling him to stop talking in all chat and turn it off. Only to ping to communicate but he fails to do so. I send him multiple types of videos to help him play league better and act better but he says "he knows this already" and just brushes it off. He's a good friend but he's a terrible CoD mentality when it comes to league. Anyone have any suggestions to help this guys toxicity? Other than tell him to stop playing because that won't happen.