Thank you Carl for confirming what I have feared. 😫
Apple has a tutorial on what to do before getting rid of one's Mac
Apple.com - What to do before you sell, give away, or trade in your Mac ...
Yes, deleting personal data is important AND easy on a Mac, as I would just need to delete the user's home directory when deactivating the account. The old notebook uses a SSD, so it would be theoretically unrecoverable even without doing a random-overwrite secure-erase. Yes, reformatting and reinstalling Mac OS X is super easy too with Internet Recovery Mode. Essentially, a "factory-refurbished-reset" will be done with the newest version of the compatible Mac OS X.
Unfortunately, Apple doesn't tell you to deauthorize 3rd party software so you can re-authorize them on a new computer. I've learned the hard way when Adobe Photoshop used to be $500. Since then, I always go through my Applications folder and check to see if each app needs to be deauthorized before wiping the drive.
