No solution
I've just been informed that the idea has been raised of demolishing the local skate park. As an adult now who has spent the last 14 years of my life skating there (since it was built in 2000), I think it would be a terrible idea to remove the skate park for the sake of a few young people who don't want to obey the law.
I live in Auckland now, but make a habit of going for a skate whenever I'm up North, and I still see it being used for its intended purpose. It may not be as busy as it once was, but skateboarding comes and goes in phases, so I'm confident it will boom again, and when that happens where will the kids skate then? On the streets? On private property? The reason it was built was to get the kids off the streets, and it was an awesome place to grow up.
Bulldozing it won't solve the issue of the few bad youth who like to loiter there. It will simply make them find a new place to do whatever it is they do.
Maybe it needs to be policed more, or put up floodlights so it's more visible at night. I'm sure there's a lot that can be done.