I can't power down my

This should be simple. It seems as though your PC is still communicating to your passport in the background. Make sure you are not copying/cutting and pasting anything to or from your passport.

Personally, I remove my thumbdrive without going through the proccess of: "Safely Removing Hardware". But this only because I know that my computer is no longer communicating to it, and because it not a matter of life and death to me if my data is erased.

But don't get me wrong, I do not reccomend pulling your device out "Unsafely". What I'm trying to say is, as a last resort, I would personally pull it out.

Anyway, completely shut down or disable all programs that may be communicating to this passport.

Then try "Safely Removing Hardware".