Currently, the only way to remove users from Schedule Maker would be to delete their enrollment for the following year, and any future enrollments you do not want them to appear in Schedule Maker for. 

As a Platform Manager:
  1. Navigate to Core.
  2. Hover over Users
  3. Select Edit User Profile Data, search and select the student.
  4. Scroll to the lower left under System Information.
  5. Select Student Enrollment.
  6. Click Edit to the right of each enrollment row > Delete.