To dispute a posting on your credit report, you can dispute by mail or online.
To dispute by mail, send the Upward a copy of your credit report, a copy of your identification, a letter stating what you are disputing, and a copy of bank statements or other supporting documents. To dispute an item online, click on the link for the credit bureau you would like to dispute with.
Equifax: https://www.equifax.com/personal/credit-report-services/credit-dispute/