Other questions

I wish I could post a loud buzzzz followed by WRONG ANSWER.

I have used Quickbooks desktop for many years... actually decades.
At one time I had 6 companies, and a few partnerships and a couple of trusts all running from a server at our office. At one time my primary business had payroll through ADP but I ALWAYS entered information by hand in QB and we had NO banking integration or online ANYTHING connected to the server or system running Quickbooks.

When I had to upgrade due to Windows 10 I was doing some bookeeping for an external company that had payroll running on Intuit.  That was not a problem - that company gave be an email address [email address removed] and I used that to do payroll for XYZ company with no issues - XYZ was using Intuit payroll through their accountant.

THEN I UPGRADED to this Quickbooks Desktop...
when I migrated my primary company - lets call it ABC company - I used my email [email address removed] to register the software and to log into my migrated company.  That worked ok but I was dismayed to be forced to go to INTUIT to verify that.

The next day I went to do payroll for XYZ Company and my password was rejected for [email address removed]

To make this nightmare a little shorter....
I had to start using my ABC account on XYZ! WHY?????

Oddly enough XYZ company got fed up with INTUIT as this started happening with ALL of their customers who paid for payroll through them and they have since STOPPED using Intuit Payroll.

As I migrated my 3 companies  (micro businesses with no employees) I started having issues with login requests. I DO NOT WANT a unique INTUIT account for each... I do not want to put ANY Business information on INTUIT - I bought the desktop version for this reason. I ONLY want to TRACK offline and generate reports for my accountant, print checks and STAY SAFE.  I have NDAs with my clients as a consultant. I do not ever put anything about my relationship with my clients anywhere online. I do not ever and will not ever integrate any online services with QUICKBOOKS or any financial institution.
I did finally manage to delete a couple of dead users - literally 2 had died and one had left the company - years ago.

THE ONLY solution I have heard in the real world is to grab a copy of an older version of Quickbooks desktop, set up a VPN running a stable old version of windows, secure the VPN to not have ANY internet access, and rebuild your company from the start of the fiscal year.  Check with your accountant of what to put for starting balances that may impact ongoing reporting for tax purposes.
NOTE - I do not like the idea of running out of date software or operating systems but that seems safer in some ways than giving information and access to a business that does not listen to their customers or understand their needs.

We live in troubling times when it comes to privacy and security
and INTUIT really truly is not listening.

Funny thing - when the email came through today telling me there was an update to this topic my email client put a big red security warning on it. 
Way to go INTUIT - don't even test the security viability of your communications.
I mean why bother? Am I right?