If there are materials from earlier course sites that you wish to save, there are two quick and easy options - or you can do both:
You can create a course backup file and save it to Google Drive or other storage. This file will later need to be restored within Moodle before you can pull out individual items, but it maintains the organization of the files more exactly.
You can download all instructor files and save the resulting folder full of files to your Google Drive or elsewhere. This allows you to pick-and-choose to re-use individual files but does not maintain the course structure.
Note: we suggest you also print/save your course page as a quick visual record of your organization of the course.