A free program for Android, by klb studio.

The Background Changer app isn’t like your ordinary photo editor, as it works like a smart background remover. It’s perfect for cutting out pictures and removing unwanted objects in the background. You can also use it to completely overhaul the backdrop of the image.

With a single touch using the Auto Erase feature, you can easy get rid of the background, while Manual Erase lets you rub your finger across the screen to remove selected parts. Some features include Lasso Eraser, Restore, Undo, Redo & Zoom, and Adding Background.

All of these features are very easy to use and you won’t have any trouble figuring it out.