You can delete Question Banks that you no longer use.
Please note that deleting a question bank will affect any quizzes that are associated with the question bank, especially if they have student submissions. For students who haven't yet taken the quiz, they won't be able to see any questions from the quiz bank, but any existing quiz submissions will still show the previously included questions.
In Course Navigation, click the Quizzes link.
Manage Question Banks
Click the Settings icon  and click the Manage Question Banks link .
Delete Question Bank
Click the Remove icon.
Open Question Bank
You can also delete a Question Bank by clicking the name of the Question Bank.