Editing Feed to Fix XML Parsing Error – Junk After Document Element

I am unable to validate my feeds with Feed Validator. I understand the problem and have read about the fixes. Where do I access the https://media-proinc.com/ribblog/feed file to edit it. It is not located in my site files. Do I edit it in Word Press dashboard?

Please advise. If anyone wants to look and the entire error documentation from Feed Validator, here it is: Feed Validator Report.

Thanks.