The best way is to contact xbox support directly and once they prove your of age and the owner they will give you step by step instructions to reset the system for the parental lock.

However there are some forums online, here is a link to one that shows how to reset:

http://forums.xbox-scene.com/index.php?showtopic=613651

I do not put in my own words because I cannot prove a persons age and hope you understand.

If you need any further assistance just let me know.

Thanks,

Joe

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