Wired
First, open the Settings app on your iPhone, go to "General" and select the option "iPhone memory". At the next level, you should see under Recommendations the entry "outsource apps". Touch Activate on the right to turn it on.
Settings → (your name) → iTunes & App Store → Unload Unused Apps
Alternatively, you can also turn it on in the iTunes & App Store Preferences. Open the settings app on your iPhone and tap at the top of your name. Then select "iTunes & App Store" and check the box to the right of "Unload Unused Apps".
Manually swap iPhone apps
If you do not want to wait until iOS throws the apps from the iPhone, you can also outsource them manually. Go back to the settings under "General" → "iPhone memory". Below you can see all your apps sorted by size. For each app you will also see the date of last use. So you know which apps you have not used for a long time and you can remove them accordingly.
If you choose an app, you can outsource it in the next step. The space used by the app is freed, but its data is retained.
If you want to delete the application complete with data, you can do that here as well. Should you later want to reinstall the app, the data will be restored – provided it is still available on the App Store.
Sometimes it happens that an app can not be reloaded after the removal, because it is no longer available in the App Store. Or it comes due to a new iOS version to problems when reinstalling the app. Therefore, you should think carefully whether you want to use the automatic outsourcing. If not, you can deactivate the function at any time.
Disable iPhone apps
Settings → (your name) → iTunes & App Store → Unload Unused Apps
Of course, you can also undo the automatic removal of apps. Go back to the Settings app, tap on the top of your name and select "iTunes & App Store". At the next level, tap the bottom of the switch to the right of "Swap Unused Apps." Now your apps will not automatically be removed from the iPhone.
Source: iPhone Tricks