Hello northaccounting,
Welcome! It's awesome that you're helping your client out with their QuickBooks Online. If you're connected to their account as an accountant user, you have access to an accountant toolbox, which has features such as the ability to undo a reconciliation.
I encourage you to take a look at this article to learn more about this feature, how to access it, and how to ultimately undo the reconciliation: Undo your client's reconciliations with QuickBooks Online Accountant
If your client didn't add you as an accountant user, I recommend having them delete your current user access and then go through the My Accountant tab to invite you as an accountant user. They can also do this by going to the Accounting Firms section of the Manage users section in the Gear icon. Learn more here: Invite or remove an accountant
That should cover it. Give me a shout if there's anything else I can do for you. :)
