You can change the payment status in ConfTool at any time and edit or delete payment entries.
Please go to:
Overview => User and Participant Management => Participants
Search for the respective participants and select their names to see the "Details of the Participant's Registration".
Please select "Manage payments" to access all payments related to the participant.
Now, please select the payment you would like to delete from the list and then select the button "Refund or Delete payment" (see image 1).
On the next page select the button "Delete Payment".
As it was not really intended to record a payment, we recommend removing the check mark from the option "Send Confirmation E-Mail" (see image 2).