No new app needed
Remove a photo background
Lift the subject out of a picture using Photos, then copy or share the cutout.
Start with Apple PhotosIncluded with iPhoneExplore Apple Photos 
Do this
- 1Open a photo with a clearly separated subject.
- 2Touch and hold the subject until it lifts from the background.
- 3Choose Copy or Share, then use the cutout in the app you need.