It would be best to have an Accountant review and advise. The fact that there are un-reconciled transactions is a red flag that help is needed. Again, if the transactions are already in the reconciliation screen, they were added to the account register for the account in question.
Transactions can be duplicated when manually entered transactions are not properly matched to transactions that come into the bank feed. It is better to match them correctly than it is to undo and then exclude the transactions that come back into the bank feed on an "Undo", in my view. All account transactions should be reconciled, even if they need to be corrected first.
It is never a good idea to direct a non-Accountant to do journal entries to reverse transactions on an account register. If this is not done correctly it can create additional accounting errors and more work to correct them. And, if the taxes have been filed, it is most certainly not a good idea to delete transactions or make journal entries that could impact the 2018 year-end account balances. Filing an Amended return increases the chances of an audit, which is not ideal.
