We do not support turning off the camera via the app. There are two ways for your reference.
1. Power outage the camera.
2. Open the Yoosee app and open the settings page, then drop down the list. You will get the Delete camera option; click it to delete the camera from the app.
Note: If you choose this way, you will lose connection with the camera, and it will work after you reset the camera to add it to the app.