Trolling and trollers

Can we get an option so we can report trollers since they are in 1 of 5 games i play every time i want them to get banned they ruin the game for everyone. everyone has dealt with this before they throw the game because they get mad and childlike. In ranked too when i was in series along with 3 other people this rengar gets mad because someone commented on his jinx banned and throws the game just because of that it just makes people want to leave the game forever if people are going to be like this and not play right and just ruins it. i will always remember that single game when someone ruins it for others because they cant grow up happens to much in normals and ranked. Happens in ranked too often