To duplicate a tasklist, click on the More actions icon at the top right corner of a tasklist.

Select Duplicate Tasklist. This will create a copy of the tasklist along with all the tasks inside it.

To delete a tasklist, click on the More actions icon at the top right corner of a tasklist.

Select Delete Tasklist.

A dialog box will appear to ask for your confirmation. Click on Yes to permanently delete the tasklist.