Yes. Students who have already submitted and received a score will maintain that score. For example, if you have a 10-question quiz, with each question worth 1 point, and you delete one of the questions, the students who have already taken the quiz will still have their attempts worth a total of 10 points, while students who take the quiz after the question is deleted will have their attempt scored out of 9 points.
Considerations:
The overall point value of the quiz in the gradebook, the one that you set in the quiz details, may be a different number from the total points of the questions. To learn more, please review Learn: Points
Students who take the quiz after the question is deleted will have a higher score as students who got the same amount of questions correct, given the decrease in total points.
Is there a way to provide partial points for a question?
Currently, partial credit is available for Fill in the Blank, Matching, and Multiple Answer question types.
The Multiple Choice question type also has an option to Vary points by answer, which allows instructors to set different point values to each answer option.