Someone posted in another thread that they were able to fiddle with a pair at an Apple store, and that you can indeed manually turn them by holding down the digital crown for 10 seconds.
I own a pair and try as many combinations as I can think of, I can not reproduce this.. i.e I can not manually turn it off by any reasonable combination of button pushing.
I manually disconnect it from everything, still no joy.
If I hold down the crown, it evokes SIRI, keep holding down, Siri says, I didnt get that, keep holding down.. nothing. it is still active. if I talk to Siri after 10 seconds of holding down, she still responds.
If I hold down the transparency select button for 10 seconds, it just switches state but doesn't turn off. I can still connect to it etc.
If I Hold down both buttons for 10 seconds, Siri gets confused, I get confused (awkward), and my volume button (crown) doesn't seem to work right, but eh, still doesn't turn off.
It may be there is something I am forgetting to disconnect and that is preventing it from turning off, but so far, no luck