uninstalling norton antivirus

[steve]

i am a new xp user.............i am trying to uninstall
norton antivirus and re-install it.
i keep getting message saying that the 'system
administrator' will not allow the uninstall???

as far as i know i am the only user on my home based
pc .this pc is a new build machine and not secondhand'.
i cannot install antivirus over the old one as it has to
be uninstalled first!.???............