Why I can't delete pictures from my Samsung Galaxy S6 Edge Plus?

[AC Question]

I have tried to search it up on Youtube and Help, but it does not work at all.

 

[B. Diddy]

Welcome to Android Central! What app are you using to try to delete? The Gallery app, the Google Photos app, or a file manager? Are these photos stored locally, or are they in the cloud (i.e., Picasa or Google Photos cloud pics)? If they're in the cloud, you can't use the Gallery app--you have to use the Google Photos app.