To remove the grade plan from the course, you'll navigate to:
  1. Core > School > Departments & Courses
  2. Edit the appropriate course
  3. Click Grading
  4. Remove the grade plan group
If you cannot remove the grade plan group, this means that this course already has grades recorded for this grade plan group. You would need to remove those grades from the grade plan group.

The other option is to remove the grade plan from the report card. To do this, you'll navigate to:
  1. onRecord > Performance > Grading
  2. Report Card Builder
  3. Edit the appropriate report card
  4. Access/Grades
  5. Edit Access/Grades 
  6. Remove the grade plans associated with this grade plan group