How to move contacts between lists
If you'd like to move your subscribers from List A to List B, you'd have to do that manually. First, export your subscribers from List A. You can export all your subscribed contacts at once or manually select the contacts you'd like to include in the export.
The file will be exported in a ZIP format. Depending on your device, to open it, you might need to double-click the file (on Apple desktop devices) or press and hold (or right-click) the folder, then select Extract All (on Windows desktop devices).
Once your contacts are exported, you can re-import them into List B.
To bulk unsubscribe from List A, go to "Add contacts", click on "Import contacts from a file", and then select Unsubscribed and Update existing contacts. Finally, click and select the list of contacts that you've just uploaded to List B and click on Next.