"unknown primary or operator" -Terminal window

You can use dot_clean -m on the USB volume to remove the metadata files.

dot_clean -m /Volumes/MUSIC

I don’t know what is wrong with your find command.

As with VikingOSX, I use the dot_clean method.

Either way, you can roll them up into an Automator Quick Action to allow ctrl-click run on a selected folder (or volume).

If you do it often, it is quite handy, but for the one-offs it only serves to “remember” the syntax.

I doubt there is anyone among us who has not had a copy/paste error caused by selection of one less, or one more character than was syntactically correct for a successful copy/paste operation.

Here is an example where Find returns "unknown primary or operator." I suggest you replace the delete operator with the suggestion in that stackoverflow post.

Personally, i use the dot_clean command syntax.

What error is returned from dot_clean?

You may have to give Terminal Full Disk Access in Privacy tab of Security & Privacy System Prefs.

Are you sure you did not let a typo creep in?

I had not trouble using a command as you posted.

The error message indicates an invalid command for find.

I got when I mispelled "delete", as in, for example

find ... -deleta