Yes. As the project organizer for your book, you can edit any chapter—even those created by other users. You can change the title and even delete the chapter, but keep in mind that if you delete a chapter, ALL content contained within it will also be permanently deleted.
To edit a chapter, click the "chapter settings" button at the top of a chapter's page.
Next, a drop-down menu will appear. From here, you can edit the chapter title, change its settings, or reorder the entries within the chapter. Don't forget to save your changes when you're done!