As long as you are the administrator on the computer and the "Supervisor" on the computer, you can make any changes you want, including turning the Parental Controls off. If you aren't the admin on the computer, or the "supervisor" in the program, then you get to live with the results.

You didn't mention the EXACT version of Norton you're using but here is a link to the Norton Parental Control program configuration instructions.

How to configure Norton Internet Security 2002 using the Parental Control Wizard

Hope this helps.