How to EDIT Approval or Reject after submission?
You cannot revert the decided outcome. In case you need to confirm it , I'd add another approval phase to confirm the previous phase, but it could happen again that the user mistake the outcome.
In SharePoint when you create an approval task, a unique task is assigned to each of the assignees (Assignees are the approvers declared in the approval task). Depending on the responses of these assignees the tasks are updated. Once these are updated there is no way we can revert these responses.
If you could explain what is your motive of editing the response we might find any other way to achive it.
Retrieving data ...