You can edit local users from the Device > Users > Local Users & Groups page.
To edit a local user
In the Local Users table, hover over the user and click the Edit icon. The User Settings page displays.
Configure the Settings, Groups, VPN Access, and User Quota options exactly as when adding a new user. Refer to Adding Local Users for more information.
In the Local Users table, hover over the user and click the Edit Bookmark Settings to configure the user bookmarks.