That sort of crap happens in every sport at junior level, bowling included unfortunately.
When I played school football and soccer the parents of some of the players were pretty ordinary, quite a few of them.
When I used to work for the football club, we used to host the Southern Junior matches on our home ground on a Sunday, and standing there for 7-8 hours working and listening to some of the biggest dickheads on the planet behave the way they did at a junior footy matches used to make my blood boil at times.
I felt sorry for the kids generally, because all they ever did was want to play footy, but then thier parents would be up in the Main Stand or on the boundary fence carrying on as if thier kids were playing in the AFL, calling the umpires and opposition players c***s and whatever else - it was pretty embarrasing.
Instead of dropping the kid from a team because of his/her parents bad behaviour, just yank the parent out the back somewhere and tell them to STFU.
If that doesn't work, ban the parent from attending.
Sometimes the worst thing involving junior sport is parental involvement, from what I've noticed.