Hi Ruth,
I see that you are using Canvas that is provided by your employer (as opposed to the free version). This means that it is up to your institution to set policies about how your courses will adhere to a term schedule, when they will become available and then no longer available, whether or not you can still access them later, etc. If you are seeking to make a back up of the content and structure of your course, you can create and download a course archive file as an option in the course settings. Then you could re-upload that archive file to an empty Canvas course in the future.
