Thanks to Hal and his withering sarcasm, and thanks to F/book and their proof of spying on everyone's computers, I have now deleted the Yahoo account with which I used to register with them.
I have also gone into a gmail account and deleted all the contacts because I am in no doubt that F/book will have that account too. This is because all the relatives I was so naively trying to "friend" were in there.
I am the last person on earth who should have gone to F/book. I should have obeyed my instincts which are usually sound, in telling me not to do something which is anyway unnecessary.
I've also checked my own profile here, to see which email address I supplied. It's another Yahoo one. If it had (STUPIDLY) been my main work one, I would have changed that too.
I have also considered asking how one deletes oneself from here, but (obeying instincts) I do not want to do that, yet. It's a good free resource, better than Apple's own user forums. However, should I decide to delete myself from here, how do I do that?
Thanks for any replies from non-sarcastic Mods or Admins.
