The following is one way to handle a customer's account after you've auctioned their unit contents.
1. On the tenant's account, post any payments that have been collected or received from auction/sales/etc. (These are often cash or check and will count as revenue in your reporting.) Make sure that if the tenant has multiple units, you are using the check boxes on the "Make a Payment" page to apply the funds to the correct unit.
2. To bring the remaining balance down to zero, enter a credit on the account for the account balance. Add a note "Bad Debt Write-Off" to the credit amount and that will be trackable on your Credit Without Payment report.
3. Move the tenant out of the unit and archive the customer account.