App has downloaded. Cant see how to delete

[AC Question]

A random app has downloaded which shows ads at the lock screen. I have to swipe to get to the main lock page. Then im able to swipe to unlock my phone.

 

[B. Diddy]

Welcome to Android Central! Are you sure it wasn't a hidden "feature" of some other app you installed? This kind of thing has been noted with apps like ES File Explorer, Flash Keyboard, Z Camera, and many others. Try uninstalling your most recently installed apps one by one, and see if the problem goes away.