Why can't I delete pictures I've sent in Google Hangouts in my gallery? I have a Samsung Galaxy Note III(3) and when I open my gallery there is a folder for each hangout conversation that contains images I have sent. 

Is there a way to delete the pictures or folders from the gallery or at least have the gallery not synced with the Hangouts application?
You can delete the photos via the Google+ app or web interface. From the left-hand menu, click Photos. If you haven't turned on auto-upload and don't want to, click Not now to get rid of the prompts. Then, if you're in the app, open the menu that slides in from the left again, and choose Albums from the menu; or in the web interface, click More on the top, then Albums on that menu.

From there you can see the Hangout photos, listed separately from the 'real' photo albums. You can select and delete them to your heart's content. Note that "deleting" a photo from this view doesn't delete it right away: it moves it to the "Trash" or "Bin". To finish them off, you can find that on the same menu you were just on, or just wait for 60 days.