I think the short answer is that you should contact your local parks and recreation department to ask for permission
or if there are any restrictions.
On the other hand, kids and their parents have been launching model rockets in parks and deserted school grounds for years, and other than loosing a rocket to either the kite-eating trees, or onto the roof of the school building, no one has been arrested that I know of in the last five decades.
I would suggest that you contact your local NAR chapter Rocket Club and ask where they launch from. With their million dollar insurance policy in place and emphasis on safety, you can't go wrong with their advice.