Oh, I didn't saw this thread, well gotta answer:
By default, friendlyfire is disabled, so if it was on, that mean players voted to active it.
You can just type !vote friendlyfire to disable it again.
About the problem of "continue teamkill", just record a video and report the player(s) on https://funandfight.nolt.io/
because the !rules forbid the abusive team kill on purpose.
And also: if a player kill too much teammates, he will die with his teammate.
I am currently thinking about add more malus to abusive team-kill (https://funandfight.nolt.io/97)