See the information at https://www.consumer.ftc.gov/articles/0151-disputing-errors-credit-reports
Nice link Carl.
Avia, I also found this piece instructive: https://www.thebalance.com/remove-debt-collections-from-your-credit-report-960376
And, I was also curious to see how much the collection could be affecting your credit score and found this piece (which wasn't able to assign a number, but does provide some additional color): https://www.gocleancredit.com/how-many-points-will-a-collection-affect-your-credit-score/
Do you have a sense of how much it's hurting (the point reduction) your score?