I wanted to wipe clean my Macbook Air (circa 2014 or 2015) and give it to someone else.
I started the process and needed to reinstall the Macintosh HD but it wasn't showing up. Same when I go to Disk Recovery, no sign of Macintosh HD (to erase and reinstall), only 251 GB Apple SM0256F Media. Do I erase that instead?
Wishing I'd just deleted all my files and signed out of everything instead now as it's a trustworthy family member!
Sounds like you are likely booting to the installer for the older OS which originally shipped with the Mac from the factory. If that is the case & you are booted to a macOS 10.10 or earlier installer, then you will need to partition & format the internal SSD using the instructions in this article:
https://eshop.macsales.com/tech_center/formatting/Mac_Formatting_6-10_R3.pdf
If you are booted to a macOS 10.11+ installer, then select the physical Apple SSD and erase it as GUID partition and MacOS Extended (Journaled) for macOS 10.11 - 10.13, otherwise erase it as GUID partition and APFS (top option) for macOS 10.14+. If booted to the macOS 10.13+ installer, then you may need to click "View" within Disk Utility and select "Show All Devices" so that the physical drive appears on the left pane of Disk Utility.
FYI, if your laptop is still able to boot normally, then I highly recommend first creating a bootable macOS USB installer so you have more options if something goes wrong after you erase the internal SSD.
Create a bootable installer for macOS - Apple Support
Macbook Air only showing 251 GB Apple SM0256F Media
