iOS 11: How to remove Portrait Mode effect after photo was taken

When Apple launched the iPhone 7 Plus, one of the biggest features was the dual-camera system’s Portrait Mode. The mode gives images a DSLR-like background blur, albeit with some hiccups occassionally. Sometimes the effect looks unnatural or just blurs key areas of the photo.
On iOS 10, if you didn’t have the option to keep the normal photo enabled under Settings, you might’ve lost a perfectly good moment. It may not have been perfect on day one, but Apple has been making impro