Originally Posted by
Ledsteplin And then, only those you share with see them.
So, that is not true. Google Photos are basically secure, but once you share a photo with somebody (anybody) and they get the URL, there is nothing to prevent them (or anyone else) from seeing the photo from that URL. That URL is not account protected or anything like that. The URL is pseudo-random and unguessable, but once it is out there and shared with anybody, anyone who connects to that URL will see the photo.
See
https://www.alexkras.com/do-not-shar...google-photos/ and
https://www.theverge.com/2015/6/23/8...vacy-protected
So, to stop sharing any photo, go to
https://photos.google.com/sharing on a computer browser, and it will list all of the photos that you have shared. You can turn off sharing for any photo that you like. Do that and nobody else will be able to see the photo.