As the seller, you are responsible for backing up any important information on your phone and erasing all personal information before selling it. You can erase your phone by going to Settings > General > Reset > Erase All Content and Settings. We also erase every phone that we receive.
You must also disable Find My iPhone before sending us your phone by going to Settings > Your Name > iCloud > Find My > Find My iPhone. Alternatively, you can do this by logging in to wwww.icloud.com/find and removing the phone from your Apple ID account. We do not purchase phones that have Find My iPhone turned on.
If you need any further help with erasing your phone or disabling Find My iPhone, please don’t hesitate to contact our customer service.