You CAN uninstall k-9 without entering a password, however, (this comes from the k-9 website)…
Symptom
You want to uninstall K9 Web Protection on a Windows computer.
Solution
Please follow the instructions below to uninstall K9 Web Protection. Make sure you are connected to the internet before uninstalling K9 so your license can be released. If this is not possible, you can continue to uninstall, but you will need to request a new K9 license if you want to reinstall K9 in the future.
Click Start
Click Control Panel. If you can’t see this option, it may be under “Settings”
Click Add or Remove Programs
Find Blue Coat K9 Web Protection in the list of programs and click it once.
Click the Change/Remove button.
Click Yes when you are asked whether you want to completely remove K9. DO NOT ATTEMPT TO UNINSTALL WITHOUT A PASSWORD. By design, K9 will block all Internet access should one attempt to uninstall without using a password. Attempts to modify K9 at a registry level will have the same effect.
Enter your K9 administration password and click Uninstall. If you forgot your password, click the “Forgot Password…” link to have a temporary password emailed to you.
When asked whether to reboot your computer, click Yes
After rebooting, K9 will be completely uninstalled.
So, technically, while ANYONE can uninstall K-9 in 3 minutes, or less, web access is still blocked.
I wonder how K-9 would react to an attempted system restore, to a restore point prior to k-9 installation?