CA Parental control prevents Norton install

I attempted to install one of my 2011 Norton Internet Security licenses on a PC that had CA Internet Security on it, (though expired).

All went as expected until it came to the uninstall conflicting software at which point it requested a password for "Parental control" to continue to unistall the CA product.

As I have never set a password and, in any case, as I've no longer got the email to which I registered the CA product to get a password reset, I am at a loss to find a way to simply get rid of the CA product.

Anyone know of a fix around?