Clearing private data in Firefox or using private browsing will stop it from working.

And obviously no one has thought they can use flash cookies to make it resistant to incognito mode, cookie cleaning or switching browsers... But yeah, this sort of technique is likely reserved for the top-priority user tracking for delivering ads.

If Johnny has the administrative rights to run--let alone install--an alternative browser, I doubt some Google password protection is really going to do much anyway.

Opening a new incognito window should do it, and deletes all local traces into the bargain...

"If you have more than one browser on your computer, you need to set the lock on each one individually"

So little Johnny downloads a browser you've not yet got on your computer.

What's the betting it can be blasted by removing a couple of cookies anyway?