It's not part of Windows so it wouldn't stop your machine booting, it may however break whatever program it's installed for. As to whether it will unblock files there's no way of knowing unless you know which programs use it.
You shouldn't be tampering with school machines and if their security is set up well they will know you did.
So in answer to your question the possible effects of deleting the service are:-
1) you get caught and end up in trouble
2) you don't get caught but you're still blocked
3) you don't get caught and you've managed to break a program in your schools computer