matching cash to invoices ... and reversing manual entry

Hi 

I have recently set up the banking facility on QB Online.  

I originally set up the link to the bank last week.  I had a few issues downloading the individual transactions, and so I added the various bank postings manually, as well as the opening balance on the bank account (as at 1 November).  All seemed good - the QB bank balance matched the Bank Account balance.  

Today I linked the QB to my bank again, and this time everything worked perfectly, with 20 or so transactions downloaded from the bank, onto the "For Review" tab in the Banking section.  

However, two receipts from the bank showing in the Review Tab, are receipts which I have already manually added, and have already been matched to the relevant invoice.  (Both receipts hit the bank on the day I performed the initial download, so I suspect there was a timing issue somewhere).  

So - I need to reverse / cancel my manual posting from last week ... which I hope will then allow me to match the deposit against the correct invoice.  Is this possible ... or is there another process I need to perform.  

Thanks all

J