The action of the Discard button varies depending on the status of the payment proposal
List of the accounts and transactions you are planning to pay or collect subscriptions from, on a specified date, using a specified bank account..
Before the Pay stage (Post and Match)
The Discard button on the payment proposal's detail page allows you to discard a whole payment proposal.
You must specify a reason for discarding, which is stored with the record for future reference and auditing.
A discarded proposal has a status of "Discarded" and you can clear its payment history.
After the Pay stage (Post and Match), if errors have occurred
The Discard button in this context removes excluded transactions from the payment. The excluded transaction lines become "Available" again.