I have a Samsung Galaxy S5. My phone has started to slow down with text messages and I'd like to delete some of the 500+ pictures in the sent/received folder. Regrettably, this folder does not show up in my gallery. I only can view it when attempted to attach a photo to a new text message, and when I do so, the option to delete is not available. I know I can view all the sent/received pictures, but then can only delete them one at a time. Is there a way to mass delete them or do I have an hour of deleting to do?