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Students who have dropped courses are not automatically removed from Canvas course sites via automatic roster uploads at the beginning of the semester due to the fact that this would also remove all records of any work completed by that student. However, students will be marked as concluded if three daily roster uploads in which their name does not appear are run.
Instructors can remove students from their Canvas course site or deny students access. IMPORTANT: Removing/deleting the student removes records of that student's completed work from the course site; a student who is concluded leaves the student's records in the course space, but the student can no longer access the course space. We recommend concluding students rather than removing/deleting them.
The following contains information on how to conclude a student in a Canvas space: https://community.canvaslms.com/t5/Instructor-Guide/How-do-I-conclude-an-enrollment-in-a-course/ta-p/744