The app that remained in Split View is now full screen in its own space to return to it, press Control-Up Arrow (or swipe up with three or four fingers) to enter Mission Control, then click the app in the Spaces bar. Move an app window to the desktop: Click the app window, move the pointer over the green button in the top-left corner of the window, then choose Move Window to Desktop. Deselect it to make the menu bar NOT appear in full screen mode. Go to the bottom of the pane and select “Automatically hide and show the menu bar in full screen” to make it always appear. Go to System Preferences > Dock & Menu Bar Preferences. You can find the option to hide or show the menu bar in System Preferences. To stop using the app full screen, move the pointer to the green button again, then choose Exit Full Screen from the menu that appears or click the button.