If you see something in the in-game chat that you want to report, right click the name to open the options and you can report. e.g., if you saw an offensive name, you can report and on the report there's a drop down for offensive name.

This PSA is brought to you by Alch & Go Industries

It's one moron, why give them the "publicity"/attention they obviously want? Just report it and move on.

You know, everyone would have played this league without ever seeing this dudes name, and you go and post it on reddit so now we all have to see it.

Rule #1, don't fucking advertise other peoples shittery. Just report the name and move on.