In order to unassign a learner from a course in a learner group, you can:
1. Click on "Users" from the side navigation bar and
2. Select "Learner Groups"
3. Once done, click on the drop-down indicated by three dots against the learner group for which the learners are to be unassigned.
4. Select "Courses".
5. Here, click on the drop-down indicated by three dots against the course for which learners are to be unassigned.
6. Select "Unassign Learners" as shown in the screenshot below.
7. In the pop-up that appears, you can select learners that you want to unassign by checking the box against their name or "Select All" and
8. Click on "Unassign Learners".
The learner will get unassigned once this is done.
Please note that once this is done the learner will lose the access to the course that he is assigned.