On an amended return there is no direct debit if you did not use direct debit on your original return.. Any taxes owed must be mailed in with a payment voucher (1040-V) or you can pay Federal taxes owed on the IRS website.
https://www.irs.gov/payments
1040-V payment voucher
https://www.irs.gov/pub/irs-pdf/f1040v.pdf
