All the photos and videos of WhatsApp are saved to the gallery automatically, So everyone can see the WhatsApp folder in your in your phone gallery. Everyone have many secrets, We would like to hid that all from friends and other relatives. Don't worry !!! we can hide WhatsApp gallery by installing a Android App.
Also read : How to change WhatsApp phone number
Note:
If you are using Apple go to Settings > Privacy > Photos > Off the WhatsApp.
The photos in the gallery are just hidden, not removed permanently. So whenever you need, it is also possible to recover the hidden photos.