As the title states, we can create a to-do list by going into the build menu and clicking the plus-sign or entering a number for a structure of our choice.
This will add items to the to-do list on-screen in a window on the right side.
At the bottom of that window is a button 'Clear List' which, when clicked, should remove the entire list from your screen.
In the current experimental version it will leave 'N/A0' on-screen without the window itself present.
If you want to create a new list after clearing the old list, the N/A0 will still be part of the newly created list.
Going back into the build menu will enable you to remove this message by clicking on the 'minus-button' next to that text: