How can I clear quiz attempts so I can add or remove questions?

Moodle will not allow you to add or remove questions from a quiz which has been attempted by students. In order to add or remove questions, you will first need to delete the quiz attempts.
To do this:

• Click on the quiz
• Click on the reports tab
• You may wish to download the results before deleting them. If so select one of the download options at the bottom of the page
• When you are ready to delete the attempts, click on the “Select all” button to select all attempts
• Click on the “With selected” drop down menu, and choose “Delete”