Welcome back to the thread, richstrazdas. I appreciate you for performing some steps to fix your concern about removing a user in QuickBooks. I also recognize how vital it is for you to manage user roles and limit their access to specific tasks. Let me route you to the right support team to assist you further.

I recommend contacting our QuickBooks Online Support Team. They have the tools to pull up your account in a secure environment and be able to investigate the cause of the error you received and why you're unable to delete the old primary admin on your end.

Here's how:

1. Open your QuickBooks Account.
2. At the top right, click the Help icon.
3. Choose the Assistant section.
4. Type your concern in the Type something field.
5. Click Talk to a human.
6. Click I still need a human.
7. Click the Get help from a human.
8. You'll be routed into the How can we help? page. Then, select either Start a chat or Get a callback and fill in the information.

Lastly, refer to this article if you need steps on how you can choose what users can see and do within different areas of QuickBooks: User roles and access rights in QuickBooks Online.

Feel free to leave a comment below if you have other questions about managing your users in QuickBooks. I'll get back to you as soon as possible, richstrazdas.Take care always!