to get this working, for all 14 fields individually, you will need to be careful with triggers being used for the Update record behavior.
Make sure the update record behavior is set to trigger on the Button U[pdate being pressed, or whatever the main submit button is.
Once the update is set to trigger on the specific submit button, you can add additional submit buttons next to each file field to delete that specific file. Set the name each one to be unique like 'delete1" or "delete2" Set the value for each one to use the image column from the database.
then you can add a delete file server behavior for each delete button. Set the trigger to use that specific delete button. make sure the Delete Folder is set to the same folder as the upload behavior. For the delete file, click the lightning bolt icon and select the corresponding delete button.