Changing the total maximum points for a quiz in D2L requires extra steps if students have already taken the quiz and the grades have been sent to the grade book. It is not possible to change the maximum points on completed quiz attempts. If you need to change the maximum points for a quiz that students have already taken, such as after editing or deleting a quiz question, this will only be done in the grade book.

Full instructions as well as options to dismiss rather than delete a question can be found at Change Quiz Points to Fix Grades.