Hi, if you want to set or unset massively a list, you can easily do that by using the “massive action” page on the “subscribers management panel”, inside the Newsletter dashboard. On that page, you can perform a wide range of operations and also move users from one list to another.
You can also delete the list name, so it will not be used for filters and other stuff.
Please refer to https://www.thenewsletterplugin.com/documentation/subscription/newsletter-lists/
Regards,
Roberto