The first thing to know and understand is that you cannot send the payment to either one of the credit bureaus. If you find an old debt on your credit report belonging to a creditor who has since then closed down business, sending the payment to the credit bureau is not an option. Credit bureaus simply collect credit information about the consumers and work in repository ability.
If the original debtor has gone out of business than the likelihood is that the account has been transferred or sold to another company. That company is now the legal owner of the debt. You should now send the payment for that debt to the new owner. If the original debtor has closed down altogether without having transferred old accounts to a new company then it is possible that your account has been deleted altogether. The way to find out whether there is a new company that is not the owner of your debt or the account has been deleted from your credit history is to order your personal copy of the credit report from the credit bureau. You can get a free report from each of the credit bureaus once every 12 months. You can access your free copy by visiting www.annualcreditreport.com