How to stop your parents being so overprotective?

Try talking to them about things like GCSEs, A levels and University to remind them that you are growing up. If you're trying to get them to let you do something, build up to it slowly, E.G. if you want to go camping with a group of friends in a few weeks time, invite everyone over and camp in the garden to prove to your parents that freak hurricanes won't blow your tents away and you will all be perfectly fine.

Earn their trust.