Question:
After I have downloaded the report from SuperControl, is it possible that we edit it as it is a XML file?

Answer:
No.
The downloaded XML file has a specific structure to make it possible to transfer the date from one system (SuperControl) to another system (HMRC).
The data, which needs to be forwarded to HMRC, is automatically pulled from SuperControl and used to populate the DAC7 report file.
Any changes made to the downloaded report will most likely render the data unusable by HMRC, resulting in a failed report upload, which in turn will require you to download a fresh report and submit it to HMRC again.