UiPress templates are designed to work in seamless way which means navigating to the front end of your site from an active template will load the site within the frame.
If you don’t want this to happen then uiPress has an option to disable the behaviour.
First navigate to site settings, then to the advanced tab of the settings. Here you will find an option called ‘Load frontend outside frame’. Enabling this will force all non-admin pages to load outside of your admin template.