This allows you to empty a course of user data, while retaining the activities and other settings.
Please be warned when choosing items you will delete your chosen user data from this course forever!
You can select which user data to remove at a granular level under the categories of General, Roles, Gradebook, Groups and Activity data.
Only users with the reset course capability (by default managers and teachers) can reset a course
From Course administration select Reset and Reset Course. Review each category and select the data to be reset.
More about resetting a course on the Moodle website (may be available in English only)