There are a number of apps that will archive your photos in cloud storage and allow you to delete them from the phone, yet still preserve them to view when you want to. I use two: upthere.com, and Google Photos. But there are plenty of others: Shutterfly, box.com, dropbox.com, etc.
Upthere will store all of your data; photos, videos, music, documents and allow you to organize and share them as desired.
Google photos will actually organize them for you, based on when and where they were taken; it will also group using facial recognition, create panoramas when you take adjacent images, show you albums of what you shot on the current date in the past, and many other neat organizing features.