Since it would be extremely tedious to manually delete one at a time( over 400 transactions) would be be better to just delete the credit card and all the transactions for it as I see it is transactions from 2015 through the end of 2018 and all those dates are reconciled and taxes paid. The start fresh and try to download only the current 2019 charges and re-reconcile Jan 2019 through Dec 2019?
