Yes, a card program administrator can subtract funds from a cardholder’s Cash Wallet. You can do this through iConnectData (ICD) using the standard process for subtracting an eCash load: https://w6.iconnectdata.com/Login > Manage > eCash > Load Money > choose Subtract for the specified amount.
Because Comdata bills Cash Wallet when funds are withdrawn from the card, a subtraction from the unused balance will not appear as a credit on your account.