Screen 3 > Direct Deposti of Refund/.Electronic has a check box, which I think you checked, to start this situation. Right below that check box is Extension payment date [O]. It defaults to the due date of the tax return. If you did not check the box then YOU selected April 15

If the client wants a payment earlier then they should make an extra 1040ES for 2024 directly with IRS. https://www.irs.gov/payments

If they do not want the payment with the extension to go through, go to https://www.irs.gov/payments/pay-taxes-by-electronic-funds-withdrawal and look towards the bottom to find 

• Call IRS e-file Payment Services 24/7 at 888-353-4537 to inquire about or cancel your payment, but please wait 7 to 10 days after your return was accepted before calling.

The client can call that number to CANCEL the April 15 payment.