Just use: sudo rm - rf /

But then you won't have anything..not even an OS. Or else you could do the safer thing: sudo /usr/sbin/kernel-power-uninstall

Edit: Just to be clear I was joking about the sudo rm -rf thing. (Although it would work )

Edit2: Does anyone know if you void the warranty by installing kernel-power or just by overclocking? Because kernel-power has all sorts of useful additions. It's not just about overclocking.

You can remove your overclocking profile like this (unless you use some GUI tool):
rm -f /etc/default/kernel-power
/usr/sbin/kernel-load /usr/share/kernel-power-settings/default