There are two ways to refresh a Moodle course for the next semester
Reset or Backup and Restore
It is likely that most users will find Reset easier and more efficient. Both methods will result in a course being cleared of users and user data.
Performing a Reset of a course is permanent. It is always good practice to create a backup of your course before doing a reset. To do a reset you should be on the main page of your course. Choose Reset from the Settings block. After selecting reset, you will see a page listing “categories” from your course starting with the category term General followed by Roles, Gradebook and Groups followed by Activity Types that are in your course. You are asked to make choices of what user data to keep or erase in your course in each category. Reset does not delete any resources or actual activities from your course. For example, if you have a Quiz, you are asked if you want to delete attempts. Deleting student attempts on the quiz does not delete the actual quiz.
Performing a backup and restore of a course is another way of clearing it of user data. Begin by being on the main page of your course and select Backup from the Settings block. Backup your course without users. (Most users in the teacher role will only have the option of backing up a course without users. If you are an admin, backup the course without users.) After backing up your course without users, restore the backup of your course into the existing course. (Teachers by default only have this option.) If you see the option to backup into a new course, you may want to do that.) Either way the course that has been restored, does not have any user data.