If you need to reset a student's attempts for a single quiz, you will need to delete the student's attempts on each question within that quiz.
Step 1: At the bottom of each question, click on "Staff Debug Info."
Step 2: Enter the student's email address or username in the text box, then click on "Delete Learner's State."
Step 3: If the student score was reset correctly, you will see a green notification that the student's score has been reset. If you see a red error notification, it typically means that the student is not enrolled in the course.