How do I turn the black wallpaper off? My screen remains black even after uninstalling the app.
All you have to do is set another wallpaper!
You can use the built-in method offered by Android (from the Home screen, from the Settings app, from the Photos app, and so on). You can read this useful tutorial for more information.
You can also use Pitch Black Wallpaper Pro to set one of the hundreds of Pitch Black alternatives, shades of black, or custom colors as wallpaper: Absence of Light, Black Beauty, Dark Side of the Moon, Darkness, Darth Vader, Gold Black, Midnight Blue, Vienna Roast, Wet Latex, and many others.