I go through my friends' phones and delete pictures of myself.
Why do you go through their phones and delete pictures of yourself?
I don't like the way I look in pictures.
It's totally inappropriate to go through your friends' phones and delete photos, even if they are photos of you. If you don't want them to have pictures of you, you should politely ask them to delete them. If you continue going through their phones they might not trust you anymore.
Eh, I don't think they noticed I deleted them.
If they didn't notice fine but it's important to know in the future not to go through someone's phone.