WebViewer provides a few options to deal with user permissions. In the WebViewer constructor you can pass the annotationUser option which allows the user to only delete and modify annotations that were created with the same user name. You can pass the annotationAdmin option which means that the user is able to delete and modify all annotations, regardless of the user. You can also pass the enableReadOnlyMode option which means that annotations can be viewed but not added, deleted or modified.