If a negative balance is added to a patron account, this workflow can be used to remove it:
Retrieve the patron account and go to the Bills screen.
Select the bill with the negative balance, click on Actions for Selected Transactions or right-click on it, and select Add Billing.
A window will pop up that asks "Are you sure you would like to add a billing to bill 1234?" Click Yes.
A new window with the Bill Patron Wizard will appear. Select a Billing Type and enter in a positive bill amount for the same amount as the negative balance. (For example, if the negative balance is -$35.00, enter $35.00 for the bill.) Click Submit this Bill.
The negative balance will now be cancelled out and cleared from the patron account.
Please note in this workflow that if you use Evergreen to report financial data to other sources that this is a change to the patron account that removes the negative balance and may have effects on other financial reports.