Open the Photos app
Select the photo
Tap Edit
Use the Markup tool if available
Use the Retouch or Healing tool if your editing app supports it
If your iPhone does not have a built-in object removal tool, open the photo in a third-party app like Snapseed, TouchRetouch, or Photoshop Express
In the app, choose the object removal or healing feature
Brush over the person you want to remove
Adjust the result if needed
Save the edited photo to your iPhone