I'm here to share some information about undoing QuickBooks reconciliations.
The undo reconciliation is only available in the QuickBooks Online Accountant version. If you're using the regular one, you'll have to manually unreconciled each transaction by removing the word "R" in your bank account history. I'll show you how.
Go to the Accounting menu, then Chart of accounts.
Choose the bank account, then click View register.
Locate each transaction, then see an "R" in the checkmark column.
Select the transaction to expand the view.
In the checkmark column, select the box with the "R" until the box is blank. This removes the transaction from the reconciliation.
Once done, hit Save.
Repeat the same process on all transactions for that period.