Accidentally copied my whole Dropbox and now can't delete

I accidentally copied over my Dropbox folder onto a new external drive, and now, no matter what I do, I can't delete it.  I've even set a new location for my Dropbox, in an attempt to disconnect it from the copied folder, but the old folder keeps reappearing and repopulating with 650GBs of dropbox files.  I don't want to have to wipe the whole drive (with 4TB of other stuff), so any ideas about how to get rid of the current duplicate dropbox folder would be welcome.  I'm on a brand new mac mini running the latest version of Ventura.  If I can do the deletion from the terminal window, I'd be fine with that. I just don't need this zombie Dropbox folder crawling up out of the grave anymore.