To edit a contributor's info, login to your book. Go to Communication. Scroll down to the list of names and click on their name. This brings you to a page that contains all of their info. Change whatever you like and Save.
Please note: If you are looking to change a name on the Contributor Page, those names are taken directly from the contributor field on the recipes. You would have to view your recipes by contributor and edit those recipes with the name you wish to change.