When a course is complete, an instructor may archive a course. Archived courses are still accessible, and you can read any available content in an archived course, but you cannot make changes or edits in a course that's been archived.
By default, archived won't appear on the My courses page. You can use the filter option to see any archived courses in which you currently belong.
How to view your archived courses
On your My courses page, go to Filter and toggle the option on for Archived courses.