How do I exit out of the app ?

On an android you slide up from the bottom middle and then hit the left triangle that comes up

Hi there, we don't have any information about Litchi APP since it is not our software. We highly recommend using DJI Go 4 app for your Phantom 4 pro so that you can maximize the features and functionality of your drone. If you have another concern, please let us know. Thank you for understanding.