You can create new address books, and mailing lists within an address book. You cannot create folders within an address book.

Sorry I do have another mailing list within the address book ( I just named it wrong first time). As I said it is still working perfectly on my old Mac ( with older version of Thunderbird 38.5.0. Here is a jpg of my list . I can not slide / or even copy and paste the address from Collected addresses to another mailing list within this address book.

Can you still add anything to Collected Addresses? If not, the data file may have become corrupted. My solution to this would be to export the affected address book, delete it, recreate it, re-import the backup and then move the imported data back to the new address book.

In the case of Personal Address Book and Collected Addresses, to delete these address books you need to close Thunderbird then locate and delete the data file; abook.mab for PAB and history.mab for CA. You can't delete them from within Thunderbird.

As an aside, I don't use CA as a working address book. It will be populated automatically (if you haven't disabled this feature in Thunderbird) and will contain addresses that you may not want to use again. I make a point of visiting it periodically, filing away any useful addresses it contains and deleting the cruft. My objective is to keep it empty so as to simplify its maintenance. If I allow addresses to accumulate, they will be proffered by address auto-completion and many of them won't be of any real usefulness.