How do I exclude an individual student from a graded item in Gradebook2?
Instructors may exclude (or excuse) any individual student from an item listed in the gradebook2. When excused, the student's course grade is not affected by the student's submission or non-submission for that item.
Excusing an item often happens when a class is composed of both graduate and undergraduate students; excusing the undergraduate students from the graduate requirements and excusing the graduate students from the undergraduate requirements.
In the right spreadsheet, click on the name of the student to be excused from an item.

This displays the Student Summary dialog box for that student.