I hope I understand your question, so here goes:
1. You have a single image and two individual records for it and one of those is correct and the other is wrong?
You can not just delete the wrong one, as you have found. What you have to do is open the wrong one and edit it to be the EXACT DUPLICATE of the correct one. Do that and save it.
Then click on the correct one and open it in the new record screen. If the two records are identical or very close, it will show a MERGE ARROW in the upper right of the window. Click on that and it will open a small box window where you can click on MERGE and let it do the merge. If you don't see that merge arrow, go back to Old transcription screen where you can compare the two easily and see what needs to be fixed to make them duplicates.
After you have done that reopen that record in the transcription screen and make sure that all the information is correct.
This technique was"invented" a few years ago by another user and is known as a FAKE MERGE.
If this is not the solution, please reply with the URL of the image/records and let us see what should be done.