If your return has not been efiled and accepted, you should be able to go back into your TurboTax account and make the changes in the File section of your return. If you have your printed return and you intend to mail it, you can also manually make the change on the paper return that you printed by simply writing in a different number on the form.
You can also make IRS installment agreement by logging onto their website-
www.irs.gov/payments.
