We had to get rid of the navbar and footer sections to include some pages in an app. With this friendly plugin you can simply define some classes that should be removed if a specific keyword is provided in the url: https://morejoomla.com/products/yootheme-plugins/more-component?app=1 removes the classes tm-header (desktop), tm-header-mobile (mobile) and footer. Be aware that the footer class needs to be added manually to the advanced tab of your footer section.