I have a question about parks?

For my sweet 16 i want to have it outdoors in the park. am i legally not allowed to let people in? like if i made lists for people who can come in and bouncers at the exits... im sure ppl will crash and sneak in anyway, but just asking am i legally allowed, after i reserve it, not to let ppl in as opposed to reserving only lets me have a guarantee that no other events will b there