Before you sell, gift or recycle, wipe your iPhone
If you’re selling or giving your iPhone away, the one thing you absolutely need to do is wipe all your data from it. Not only will it contain potentially private material, such as photos, but also your Apple ID details. Depending on how you’ve set up your iPhone, that could give someone else access to your account, including billing details and the ability to buy expensive apps or media content on your bill.
One quick note before you proceed.
THIS WILL WIPE ALL DATA OFF YOUR PHONE WITH NO RECOVERY.
We’ll repeat that, just to be clear.
THIS WILL WIPE ALL DATA OFF YOUR PHONE WITH NO RECOVERY.
Finder takes no responsibility if you fail to back up content on your iPhone before wiping it. So the first thing to do if you haven’t already convinced yourself that you’ve got all your content would be to plug your iPhone into a PC or Mac running iTunes and create a backup of your iPhone’s contents.
Once you’ve done that, the first thing you should do to wipe an iPhone is sign out of your Apple ID. This will disable services such as Find My iPhone for that particular device and is a security feature designed to stop iPhone thieves from simply wiping your device and selling it.
Open up the Settings App and scroll down to the iCloud section. In that section, at the very bottom, is the option to Sign Out. It will warn you that doing so will clear Photo Streams and iCloud Drive content from the device.
Proceed, and within the Settings App, tap on General. Then scroll down to the bottom of the page. There should be a Reset option at the very bottom.
The option to fully clear an iPhone is "Erase All Content and Settings", which does exactly what you think it will do. The entire process should only take a few minutes, at which point you’ll have a completely clear iPhone to sell or give away.
If you’re at all worried, you can always set up the device as a new iPhone by simply following the onscreen prompts to check your photo galleries and such. As long as they’re clear after a reset, you can run the Erase All Content and Settings option again to reset it once more.