You can edit or delete the appearance of your list at any time
Edit the appearance of your list (e.g. topic photo, name, description, visibility)
Click on the pencil in the right corner of the topic image in the list
Change the respective parameters of your list like topic photo, name…
Delete your list
Click on the context menu <…>
Select <Delete List> (this cannot be undone)
If you want to edit the content of your lists or copy content from other lists into yours, you can find help here.