The patch made it kinda a pain.
From the scoreboard, initiate the kick, then TAB out of the scoreboard, the go into the console (tilde ~). You should see in the text above the console prompt something like:
That corresponds to the person you highlighted in the console. To kick them, just type:
confirmkick 0 reason - where reason=reason why they are kicked.
If you want to do it all in the console just put this before the confirmkick:
Personally I use the scoreboard method, then confirmkick from the console, because I want to scan the scores from time to time for obvious TK. If for example I see someone has -30 and it’s a quarter of the way through the match, then they’re booted.
Plus you don’t have to remember the name if you use the scoreboard, and you can still boot people with jacked up characters in their names, because the confirmkick command just wants a number and a reason.