So, you have some photos you don't want others to see and you don't want to delete them either. Hiding those photos is the solution. To hide photos on iPhone 6S, and other iPhone, iPad and iPod Touch devices running iOS 8, iOS 9 or later, do as follows:
1. Open the Photos application on your iPhone 6S.
2. Browse through your Albums and open the Picture you'd like to hide
3. Tap the Share button on the bottom left
4. On the second row of actions, tap the Hide button to hide this specific picture
5. Hit the Hide Photo button and your photo will no longer be shown in the Moments, Collections and Years.
Tip1: To access Hidden Photos on iPhone, go to the Album tab, find the Hidden album and open it to view your already hidden photos.
Tip2: To Unhide a Photo, go to the Hidden Album, open the photo to be visible again, tap the Share button followed by the Unhide button.