If a 1-confirmation cash-out transaction has not yet been redeemed, you may cancel it if needed, so it will no longer be redeemable by the customer.
To do so, in the Admin's Transactions panel click on the the transaction you wish to cancel, and in the drop-down click the 'Cancel transaction' button below 'Transaction Status':
A confirmation window will pop up requiring you to type the machine's name where this transaction occurred. Once done, click the green 'Confirm' button:
You should now see the result 'Error' below the 'Transaction Status' and hovering the mouse over it will show 'Operator cancel':
After which, you may refund the coins or disburse the cash manually to the customer.
⚠️ NOTE: Cancelling a cash-out transaction means that the database will be updated to prevent the dispensing of cash for a particular cash-out transaction. It will not return or offer funds back to the user, for which a manual reimbursement may be needed.