From the Admin Dashboard, select the student for whom you'd like to schedule the change from the student roster. Scroll all the way down on the student's Overview tab to the Student changes section and click the blue "New action" button to the right.
The Schedule an action window will pop up. From this window, select the "Mark as inactive" option in the Action drop-down menu. Enter the date that the student should be marked as inactive. Click "Save".
You'll see the new action appear in the Student changes section of the student's profile. To edit or delete a change you've already created, simply click the three dots to the right of the change and click "Edit" or "Delete".