Clash players are locked in team

First of all, I enjoyed the mode, very intance and fun, but after the tournament one of my teammates, who is a onetrick rengar, got mad and dont want to play this mode because he is getting targeted. So we went looking for another player, but after we found one we saw that we cannot kick him out of the group and he couldnt leave neigher. It's not fair that our team is locked on 5 players and if 1 of them cant play this day, all team is f**ked. one solution to this problem is to give a team a few subs roles the other one is to give the team an option to change roster in the waiting to the locking.