How do I "wipe clean" my old IPhone before discarding?
Erase all contents and settings. This is covered in the manual
settings -> general -> reset -> erase all content and settings
On the iPhone go to Settings > General > Reset and select Erase All Content and Settings.
This is a secure erase of everything except for the iOS version installed and the included apps.
Settings>General>Reset>Erase All Contet and Settings.
There are companies that will buy old iPhones, by the way. Might be an alternative to just binning it.
Retrieving data ...