To un-reconcile transactions, head to the accounts tab, click on the balance, scroll to find your transactions (which will be marked with a bold "R" in the far right column) and edit each transaction in question using the pencil/paper icon
and adjust the transaction from "reconciled" to "uncleared" and save your changes.
We recommend you add in a new note to the accounts "Notes & History" to ensure you have a clear trail of the chain of events. Once you have un-reconciled the transaction, it will be available for a new reconciliation.
keywords: bank account reconciliation, adjust balance