Using the script panel:
You can edit the script by clicking on the edit option below the preview, and navigating to the script section.
Here, navigate to the chapter you would like to edit, then click on the 3 dots on the top right, and you will get options to:
Duplicate chapter - This option will duplicate the current chapter.
Add chapter before - This option will add a chapter before the current one.
Add chapter after - The option will add a chapter after the current one.
Delete chapter - This option will delete the current chapter.
Click the save changes button to apply and save the changes you made.