Can't erase an old (and mostly broken) external HD

I've got an old external Freecom hard drive that I want to throw away. I think I once used it for Time Machine, but I vaguely recall it broke down, and I haven't used it in quite a few years.

How can I erase this so I can safely throw it away? I eventually dug up cables for both power and connecting to the computer. The drive does appear in Disk Utility, but does not appear in the Finder. When I use Disk Utility to erase it, I keep getting "Unmounting disk / Couldn't open device / Operation failed ..." The "Volume" (partition?) is grayed out in the Disk Utility sidebar; the physical disk itself does appear in black. When I select partitions, it tells me the volume is not mounted. First Aid instantly works successfully.

Or is this a situation when, even though the problem does not look like a nail, the best solution is indeed a hammer?

Thanks in advance!