Delete
Delete Boxes
To delete a Box, right-click on it or click on the config icon (the wrench) and select Delete. Deleting a Box will not delete the tasks in its scope. However, you will lose the Box's configuration, including the Box statuses and some items such as the markers, filters, Column Views, etc.
Bulk Delete
You can also bulk delete selected Boxes. To do so, left-click on the selected Box, and while holding down the mouse, select the other Boxes by pressing CTRL. Then right-click on any of the Boxes and choose Delete.