Put the Capption in progress, delete or replace the picture and complete the Capption again.
How do I put a Capption in-progress?
Read this article to learn how to put a Capption in-progress.
Delete the picture
Okay, now you've put the Capption in progress. The Capption is available in your app again by going to: In progress.

Open the Capption, then go to the picture you want to replace or delete. Open the attachment and swipe to the right to delete the picture.

Complete the Capption and a new report will be generated.