It looks like it can only be uninstalled with a code. From their website:
In order to uninstall X3Watch PRO, you will need a security code that proves you are authorized to uninstall the software. You can obtain this code easily by logging in to the X3Watch PRO Administrator area (On Windows, double-click the X3Watch PRO icon near your computer clock; on Mac, Control-click the X3Watch PRO dock icon and choose Open Administrator) and selecting the Uninstall Code option.
Click here to obtain your uninstall code online.
You may also obtain a code by calling Customer Support toll-free at 1-877-944-8080. You will need to confirm your authorization by providing your administrator password to your support representative.
Please note that uninstall codes expire at midnight EST of the day they are given. Your computer's date and time will need to be set correctly in order for the code to be accepted.
Here is the site:
https://secure.parentalctrl.com/x3watchpro/support/article.php?id=1058
Regards,
Captfred