There are two ways to Unassign a lesson plan.
You can unassign it in the Lesson Planner tab or in User Information.
In both ways, you’ll be asked if you want all assignments or future assignments to be affected.
If you choose all, any previous assignments will be erased from your calendar.
Choose future if you want already assigned assignments (prior to that day) to remain on the calendar.
On the lesson planner page, click on the lesson plan. (The main area, not the three gray dots.) Click on the Assigned Students tab and click on the trash can.
From the Dashboard, select User Information (on the left-hand menu). Select the student. Choose the school year in the Lesson Information tab. Click the Unassign button.