As the course owner, you can delete any course you've created. To delete a course, click on the three dots -> Delete course. Read the important information on the pop-up message and confirm the deletion by ticking the acknowledge checkbox and clicking the Delete button.

You can also select multiple courses at once by hovering over the empty area on the left side of the course and ticking the courses you would like to delete (you can select all your courses automatically by clicking on the Select all first checkbox option, or manually tick one by one) -> Then, click on the Delete option -> Check the acknowledge box and last but not least, click on Delete.

Note: You can unselect all the courses by clicking on the minus button (-) from the toolbar.