That last throw-away comment, “for more security,” suggests that there’s a little more to cover, so that’s the next topic. For more security, consider turning on FileVault encryption when you start using your SSD drive. These options are not needed for an SSD drive because a standard erase makes it difficult to recover data from an SSD. With an SSD drive, Secure Erase and Erasing Free Space are not available in Disk Utility. You’ll also want to read “ OS X: About Disk Utility‘s erase free space feature.” A note at the end starts to get to the heart of the matter. However, that Apple article skips over the nuance of completely erasing an SSD. “ What to do before you sell or give away your Mac.” Item #6 in that document launches the discussion and links to a pretty good article: “ How to reinstall macOS.” That article, by the way, has a nifty table that summarizes which versions of macOS you can install from the recovery partition. The first thing to do is read Apple support article. You’ll want to securely erase that SSD, but it’s a bit tricker than a plain hard disk. These days, because SSDs have been an option for Macs for almost a decade, it’s very likely that you have, or will soon have, a Mac for sale that boots from an SSD. Securely erasing a hard disk isn’t hard to do, and it’s been discussed in many places. Back when I did that last, the Mac had a hard disk. It’s been awhile since I sold an old Mac. If you’re planning to sell a Mac that boots from an SSD, or you have an old Flash drive or SSD you want securely erase, this article has the details.

How to clear a macbook air hard drive