How to delete an imported bank statement?

Hi there, I'm trying to reconcile my bank statement with bullet. I added a .csv back in May which listed a transaction as being paid out on 6th May but when I downloaded a new .csv from my bank for May it showed the transaction as having gone out on the 8th. I have added both .csvs to bullet and now have two payments out to reconcile where there should be only one. How can I fix this? Many thanks in advance