If you can't access the primary admin's account, we can process a transfer request. The full steps and details are found here: Request to be the primary admin or contact.
If this is about transferring the primary admin access to your client (from QuickBooks Online Accountant, we can follow these steps:
Sign in to your QuickBooks Online Accountant firm as a primary admin.
Access your client's QuickBooks Online books.
Go to the Gearicon, then select Manageusers.
Find the client's access, then click the arrowicon under the Action section.
If the new primary admin wants to track and check the current company's financials, they can run some reports. We can share this article with them if they need help: Run reports in QuickBooks Online.
If you have more questions about managing users and their roles, let me know and I'll help you out. If you happen to come across any difficulties while managing your reports or entries, feel free to add them to your reply. I'm sure we'll work something out.