iPhone data erasing help
1. Tap the settings (gear icon) from the home screen (or whatever page it happens to be located on your iPhone).
2. Tap the "General" settings menu item.
3. Choose the "Reset" menu item.
4. Tap on the "Erase All Content and Settings" menu item.
But this won't completely erase your data from iPhone, and the data can be easily recovered by some data recovery tool.
So, I suggest you try Safewiper iPhone data eraser to wipe your iPhone clean without recovery before selling.
Safewiper is a professional data wipe software which can help you erase everything from iPhone.
Can you please tell us what exactly you are going to do once your iPhone is reset?
So I can explain it in a better way.
Before using this method, you should make sure that you have synced your iPhone to the computer in recent times.
This method requires your Apple ID and password.
3. Paid third-party software
such as a useful windows unlocker called joyoshare ipasscode unlocker, it also has mac verison.
2. Use a data eraser tool in the market to do this job for you.
Note: Sync and back up your important data first to iTunes or iCloud so that you can recover data with tool, like D-back, Joyoshare iPhone Data Recovery, Dr.fone, etc. after erasing data.