When you ban a mon and a player that isn't first pick decides to Troll

So Here we are in the champ select screen. Is it wrong to tell people at start that you will ban a mon especially if they are not first pick.. This guy was 3rd pick, i called out before anyone else started chat that I would ban Yas. After i said this and banned him this guy just started acting like a 4 year old that didnt get his way. Am I wrong to ban? and how do we report people like this if someone takes the hit and dodges so that we all do not get penalized because of someone trolling us all?

Champ selection Chat:

: sorry man im banning yas i ban him everygame : i gotta troll your lane now : well if u dont unsderstand why then and if u troll i ll just report u : youre getting trolled : ** : and ill record game to have proof : ok : do it : sure will : imma troll pickl : imma troll your lane : then imma troll so more : can someone just dodge : just repor this guy : report all and dodge : come on guys : spmeone dodge pls : i cant im at silver 5 at 0 because of ppl like this : youre fucked : idiots this game : yea you : what a douche Eclectic God left the room.

love to see everyones thoughts, I removed the names this time!! :) Champ selection Chat:

: sorry man im banning yas i ban him everygame : i gotta troll your lane now : well if u dont unsderstand why then and if u troll i ll just report u : youre getting trolled : ** : and ill record game to have proof : ok : do it : sure will : imma troll pickl : imma troll your lane : then imma troll so more : can someone just dodge : just repor this guy : report all and dodge : come on guys : spmeone dodge pls : i cant im at silver 5 at 0 because of ppl like this : youre fucked : idiots this game : yea you : what a douche Eclectic God left the room.

love to see everyones thoughts, I removed the names this time!! :)