Warning From CNET: iPhone "Restore" does not delete personal data! So before reselling or giving away your old iPhone 5C, you should erase all your personal or private data on iPhone 5C, and make the iPhone 5C as a new one.
> Erase All Data on Your iPhone:
Contacts, SMS Text Message, Call History, Calendar, Email, Note, Reminder, iTunes DB, App (and generated data), System setting, Apple ID, Photo, Video, Voice memo, Keyboard Cache, Safari Bookmark, Passbook, and more
> Erase Traces of Deleted Files:
Contacts, Messgaes & iMessage, Call Logs & Facetime, Calendar & Reminders, Notes, Voice Memos, Safari Bookmark, Photos