I have one particular external HD that insists it is still in use, when I know I have closed everything. Now I don’t even ask my computer if it is safe to remove it, because I know it is and it will tell me it is not.
There seem to be different names in use for these little devices. I call them Flash Sticks, because you know, the small ones are sticks and they flash!
My sister in the UK calls them Memory sticks. I believe they are also referred to as USB or U, pen, thumb(nail), drives or sticks.
Removing these little guys isn’t too much of a problem. My main frustration is when you have stayed up a little too late watching ‘stuff’ online and now you really need to go to sleep. You try to shut down your laptop, only to be met with the Windows statement, Update and Shut Down or Update and Restart. No other options! Grrrr!