The 'real' question was & still is, can we find a way to delete the files on my son's thumb drive. Since no-one knows how this can be done, I suggest we stop flogging a dead horse.
Way back in post #55186, joemike suggested that you may be able to delete the files on that drive by changing its permissions...
At the bottom of the Info window look at Sharing & Permissions (scroll down to the bottom of that image)
If that indicates you have "Read Only" permission,
Click on the padlock at the bottom right corner of the Get Info window
Enter the password for your administrative account
Change your privilege to Read & Write
So far, your
only response to that spot-on suggestion has been that you don't see a padlock.
A mystery, true, but until you address the drive's current permissions and whether you're able to change them
without regard for the missing padlock the horse is still alive and, if not necessarily well, at least breathing.
The mystery of the missing padlock has totally diverted this discussion from the possibility that your problem may have an easy solution
that's already been posted!More: And on the other hand, I just found this in a post from 2014: "OS X does not allow the usual file & directory permission on MS-DOS (FAT) disks, so you can't try to make it read/write."
