This article explains how to remove a learner's access to a course.
Click Community. Make sure you're on the People tab.
Select a learner.
Click Courses in the left panel.
Locate the course you wish to remove the learner's access to and click on the Actions icon [...] and select Remove from course.
Confirm that you'd like to remove the person as Learner from the course. Click on the Remove button at the top right.
To learn about how to delete a learner from your school, click here.