Deleting transactions

Hi

Sorry if this has been asked before - I have had a look through the previous questions but can't find what I'm looking for.

I'm not trained in accounts, I use Sage for our family-run business so apologies if I'm asking silly things :)

When reconciling our banks, there are a lot of transactions showing from previous years (most likely duplicates). I've spent a lot of time over the past week making note of all the transactions showing on the bank reconcile page which will definitely not be reconciled in future statements (some duplicate bank payments going back as far as 2018). I thought I had it all sorted, but then when going back onto the reconcile page, all of the transactions I deleted are still there, but the reference has changed to say "cancel". If I go back into the transaction to try and delete it again it says "This transaction has a reference marking it as reversed, therefore this change cannot be allowed" What does this mean, please?? Really hoping I haven't completely messed everything up D: Is there any way to remove these transactions so that they aren't showing when I open the bank reconcile?

Thank you!