Are you using the administrator account?
If you are using the adminstrator account you can try the suggestions listed here: http://winaero.com/blog/fix-you-do-not-have-sufficient-access-to-uninstall-a-program-please-contact-your-system-administrator/
I would add that you are best backing up your registry using something like ERUNT before doing this and if you are not confident with the registry then it may be best to avoid it as it can have devastating effects if you get it wrong.