TreePress is designed to help you display family information. You can control what is displayed by using the Family Groups or by simply leaving some fields blank – but the plugin is not designed as to act as a user management tool.
WordPress has some built in tools to control visibility – for example, in the back end side bar on the right of the screen ‘Publish’ section there are options to set a page as Public, Password Protected or Private. If you are using our Shortcodes to display a tree in a page or post, these WordPress settings may give you the control you needs, otherwise we recommend you search on the WordPress repository for Membership plugins if you need to control access to your site and the visibilty of pages.