1). Stop Storing Texts-
To stop your phone from saving texts forever, open up the Settings app and tap Messages. Scroll down until you find Message History and tap Keep Messages. Change Forever to 30 Days or 1 Year. A pop-up will ask you if you want to delete older messages; tap Delete to proceed.
2). Don't Double Save Photos-
If you use your iPhone's HDR mode or Instagram a lot, you've probably noticed that your phone automatically saves two photos: the HDR version and the normal version (or, in the case of Instagram, the filtered, cropped Instagram version and the normal version).
To stop double-saving HDR photos, open the Settings app and go to Photos & Camera. Scroll down to the bottom and untick the toggle next to Keep Normal Photo. If you have an iPhone 7 Plus, you'll see a similar toggle for Portrait mode that you can also disable.
To stop double-saving Instagram photos, open the Instagram app, tap your profile tab and then tap the Settings (gear) icon in the upper right corner. Under Settings, untick the toggle next to Save Original Photos.
3). Stop the Photo Stream-
To turn Photo Stream off, open the Settings app and go to Photos & Camera and toggle off Upload to My Photo Stream. The photos in your Photo Stream will be deleted from your iPhone, but they will remain on any other devices (such as your iPad or computer) for which you have Photo Stream turned on. They'll also remain on your iCloud account for 30 days from the date they were uploaded.
4). Clear your Browser Cache-
If you use Safari all the time, your iPhone may be storing web history and data that you simply do not need. To clear Safari's browser cache, open up the Settings app and tap Safari. Scroll down and click Clear History and Website Data.
5). Delete Downloaded Music-
Those playlists and albums you downloaded to rock out on the subway can start to add up. If you use Apple Music, it's easy to find your downloaded songs to delete them. Go to Settings > General > Storage & iCloud Usage > Manage Storage and find Apple Music on the list. You can swipe to delete individual songs or you can swipe on All Songs at the top to delete all.
6). Delete Downloaded Podcasts-
Similar to music, you might also have a number of podcasts downloaded to your iPhone. Unlike music, it's doubtful you'll return to a podcast for repeated listening. If you use the stock Podcasts app, it's easy to delete your downloads. Head back to Settings > General > Storage & iCloud Usage > Manage Storage and tap Podcasts. There's no way to delete all at once, so you'll need to go down the list, swiping to delete the podcasts for each show.
7). Delete your Reading List-
Safari's offline reading list can take up unnecessary space saving web pages for you to read when you have no internet connection. To clear Safari's offline reading list, open up the Settings app and go to General > Storage & iCloud Usage. Under Storage, tap Manage Storage > Safari. Swipe left over the words Offline Reading List and tap Delete to clear the cache. Doing this will not delete individual items from your reading list: To do that, open the Safari app, go to your Reading List and swipe left over items you want to delete.