K9 Web Protection is pretty much tamper-proof. Trust me, I've tried deleting it myself because my mum installed it, nothing helps lol.
Your best bet is to wipe your laptop completely, and restart, after backing up your files. You can do this with an XP, or vista disc, whatever you use, and then re-installing all your things back onto your laptop.
To be honest, your wording doesn't make you sound like you were the person who bought this laptop, sounds more like a child trying to break parental controls, and you know this isn't a case that could end up in court, there's been no offence commited. If you're not, do as I have said. However, if you're simply trying to break controls, they're there for a reason. I've seen, and used the old 'laptop with K9' trick plenty of times.