Had this "smurf" in my Blind Pick lobby

And the first thing from him was this:

if you feed I go afk!! I do not play any lost games!! I am dia2 smurfer and this is my smurf account,is ok for report me have fun!!

We didn't answer him or write anything since we had all called our choises already (except him). After we didnt answer him he said he was gonna throw/afk or something.

Thankfully, someone left the lobby and the game was cancelled. But i would stil REALLY like to report him/get him banned, but how do i do that if the game didnt even start? Isnt there some kind of lobby chat logs or something?