Another way would be to delete your .pwl files. These are your password files. Be careful, if this doesn't work you might want to restore them after you put them in your recycle bin.

If your problem was that you installed your parental control software and since uninstalled it, you might want to reinstall it and contact the manufacturer to figure our a way to get it back. I was in this situation myself and it wasn't until I was able to delete the original password from the software that I was able to correct the problem.

On the other hand if you just used the standard Windows content advisor just go to start>settings>control panel>internet options>content and undo - or uncheck what you checked.