Many thanks indeed. Yes, it is quite a number of folders. I'll check out the 2nd option.
BTW...,
I just thought the following possible workaround.
Something I believe is not (yet) available within Opus is to change a folder modified date after oldest/newest date in that folder.
In flat view/show files only I could filter the files on 'delete', select them all, change the create/modified date on whatever old date - January 1950 or something.
Then have the folder modified date changed after oldest date, so, to 01-01-1950, sort folders on date and delete them.
A tool like SetFolDate can do this or a script as in
Anyway, thanks again.