I've just followed the steps here to try to format my wife's laptop so we can sell it: https://superuser.com/questions/959422/reinstall-os-x-without-cd-dvd-or-apple-id
Unfortunately I'm still getting a message saying "to download and restore OS X, your computer's eligibility will be verified with Apple" and when I proceed further in the installation, it says "signing in to App Store" and there is nothing I can do but sign in.
It's my understanding that the Apple ID needs to have the relevant OS X paid updates (so in this case, El Capitan) so if we sell it in this state, wheover logs in with their own Apple ID won't be able to use it.
Any suggestions on how to restore it back to it's original state? Many thanks