At the age of 16 (in the UK) you have the right to walk out of your parents' home and never have any contact with them again. (NB: I'm definitely not recommending that as a course of action! I'm simply stating that it's your legal right to do so). If your parents were to report you as 'missing' to the police, and the police became aware of your whereabouts, they would not be permitted to tell your parents where you were (although they could tell them that they'd found you safe and well).
Chris