I am not a pro-Mac user (I am a Windows user)
Here's what I did with my old Macbook Air,
- Press COMMAND + R while booting and it went into the mode shown in the picture
- Selected Macintosh HD to (hopefully) install Mac OS X again
- Entered Apple ID credentials
However, upon logging in, a message box shows saying that the Apple ID has not been used with App Store then the install won't proceed.
What can be done to format the Macbook Air into factory settings.