You can duplicate or delete a Course directly from the main Courses page.
Once presented with your list of courses, you can duplicate a course by clicking on the duplicate logo (No. 2 in the image below).
To delete the course, select the 'dustbin' logo (No. 3 in the above image), which can be found right next to the duplicate logo.
Alternatively, you can also delete a lesson by clicking on the lesson you want to delete, scrolling to the bottom of the page and then choosing Delete. You'll be asked to confirm deletion by typing DELETE into the entry field. This is to avoid any accidental clicks.