I have an old duplicate credit card entry that the GST has already been paid to Receiver General. How do I reverse this transaction without affecting taxes?

Hello chrisring111-gma, 

Welcome to the Community. QuickBooks Online is a hassle-free program that simplifies the way you manage your accounting. I'll be glad to point you in the right direction so you can achieve your QuickBooks goals. Recording your transactions the right way is a good exercise for keeping your books accurate.

To ensure accuracy in your books, I recommend contacting an accounting professional to get expert advice on how to reverse the transactions without affecting taxes. Doing this will help prevent any future discrepancies in your books. You can also reach out to accounting professionals on our site using this link here.

I'll also leave this question here so other accounting professional members can chime in and share their expert advice. Let me know if you have other questions, I'm here to assist.