In order to hide pages, click on the 'Manage properties of this page' icon in the lower right side of your Voog menu. There you'll be able to see your current page title, URL, layout, description, visibility and the option to either show changes performed on this page automatically or not.
Once you're ready to change your page back visible, simply access this same menu and select 'Visible in menu' from the 'Visibility' menu.
As an alternative, you can also either hide or reveal your pages via 'Structure' menu. Simple access it from the 'Content' panel and proceed to the correct language from the upcoming page.
Then click on the 'Settings' link behind the desired page name to access the menu where you're able to configure its visibility.