2 methods: Submit a dispute to Experian online Submit a dispute to Experian in writing
When you want to improve your credit score or remove an item from your credit report that is incorrect, you must file a dispute with Experian, which is one of the top credit reporting agencies in the United States. You can file the dispute to Experian online on your website or send a letter with details of it.
File a dispute with Experian online
Get a copy of your Experian credit report. You can get a free copy of your Experian credit report once a year either by logging on to www.AnnualCreditReport.com or by calling (877) FACTACT.
Identify the credit elements you would like to dispute with Experian.
Visit the Experian Disputes Center on their official website http://www.experian.com/disputes/main.html.
You must initiate your dispute within 90 days of receiving your Experian credit report. Your credit report will have a unique report number that is only active for 90 days before it expires.
Place a checkmark next to “Start a new online dispute,” then click “Continue.”
Verify that the tick is next to “My credit report has a report number,” then click “Continue.”
Enter your personal information in the fields in the Personal Credit Report dispute page. You will be asked to enter your credit report number, social security number, state, and zip code.
Check and place a checkmark next to each of the three details in the Terms and Conditions field.
Click “Submit.” A copy of your Experian credit report will appear on the screen.
Locate the element of credit you want to dispute with Experian.
Select the option next to the credit item that says “Dispute this item”.
Select all the details that justify your reason for disputing the item. Examples of these details you can select are “Wrong balance”, “Account paid in full”, “Bad balance history” and many more.
Enter your email address in the field at the bottom of the report. After the inquiry about your dispute is over, you will be notified of the outcome via a message to your email.
Select the option to submit your dispute to Experian.
Expect to receive the results of your Experian dispute within no more than 30 days. During that time period, Experian will conduct an inquiry into your dispute with the source of the credit element. If the dispute goes to your favor, that particular credit element will be removed from your Experian credit report. 
If the dispute is not in your favor, you may have to file another dispute with Experian in writing and include physical evidence that proves that the credit element has an error on the part of Experian or the creditor.