How do I delete a list, and what happens to the to-dos inside it?

Hover over the list in the sidebar and click the × that appears, then confirm. Important: deleting a list permanently deletes every to-do inside it — they are not moved to the Inbox. This matches how your Supernote behaves, where deleting a list deletes its to-dos too. The confirmation warns you and shows how many to-dos will go.