If your custom Smart List is not working as you want it to, you can edit it to add or remove filters or change the name, color, or icon. Here’s how.
If you decide you just want to start again, you can delete a Smart List the same way that you delete a list in Reminders.
When you delete a Smart List, tasks are not deleted. Tasks remain on the same list that they were originally assigned to, or on your default list if you added tasks directly to a Smart List.