Hi Dan,
We do have the setting named as “Automatically Delete Abandoned Orders after X days” under Settings tab for automatically delete the records of the abandoned cart from Abandoned Orders tab after the days which you will set in the setting. But it will delete all the carts ( Guest carts, Registered carts, and visitor carts).
In our supporting system tool, I have noticed that you have created the ticket for the same issue. I had replied you on it on 14th December. But it seems you are unable to deliver the same. I have again sent you an email with the detail description through the ticketing system.
Can you check the Inbox or SPAM folder of your email address?
Regards,
Chetna Bhutka