If you want to remove a student from a specific course then you can do that through the Student Dashboard.
Use either the student search function or search manually through the membership or course that the student belongs to in order to locate them.
Click on the students name.
You will then see a list of the courses the student belongs to. To the right of the course name select the dropdown:
Click on the 3 dot dropdown under the category 'Actions'. Then click on 'Revoke Access' to remove the students access to the course.