new buyer cannot log in to the mac mini I sold him

What to do before selling or giving away your iPhone, iPad, or iPod touch "Use these steps to remove your personal information from a device, even if you don't have it anymore." Click here --> What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

timfromgloucester wrote:

I failed to switch off "find my mac" when I sold my old mac mini and my buyer is understandably miffed that he cannot log in with his own account.

As far as I can see from reading various comments, does the buyer need to be given my Apple ID and password so that he can log in with that, switch off 'find my mac'

No, do not ever give out your AppleID or password.

Sorry to be such an ignoramus! I am not even sure I have spelt ignoramus correctly......

Not a problem, it is always wise to ask questions when you do not understand a topic. Some of these Apple features can even be confusing to more experienced users since some of the Apple documentation is not clear on many aspects. I just went through an issue with my AppleID setting up a new Mac....I can certainly say the macOS prompts & info is severely lacking in details at times on some of the finer points of these features. I've seen a few experienced contributors on these forums debate how some macOS features (AppleID & iCloud) work...each had seen & experienced slightly different behaviors with their systems.