them. respect their privacy and delete the photos and let them watch. by allowing them to take a look, they themselves can also see that photos are really gone, and you get out of the way so quickly.
if you meet someone you want to photograph, then first have a chat with this person to make them feel more comfortable. this way they are less tense and they agree faster with taking a few pictures. by showing the people the photos, there is also a higher chance that you can make more photos. 