You will need to log in to your TurboTax Online account, click to get back in to your return, and once in your return step through the File section until you get to the area of your return where you enter your tax payment information. You will be able to choose your payment options there. 

Once your return is accepted, information pertaining to your payment, such as account information, payment date, or amount, cannot be changed. If changes are needed, the only option is to cancel the payment and choose another payment method.

Call IRS e-file Payment Services 24/7 at 1-888-353-4537 to inquire about or cancel your payment, but please wait 7 to 10 days after your return was accepted before calling.

Cancellation requests must be received no later than 11:59 p.m. ET two business days prior to the scheduled payment date.

This number does not work and IRS number they transfer you to [phone number removed] is a dead end, you cant talk to anyone.

Per the IRS link for installments, "if you are unable to revise an existing installment agreement online, call us at 800-829-1040 (individual).  Plan and expect to be on hold for awhile at this time of year.

the [phone number removed]  number doesn't have any live reps answering now.  how else can we change our payment plan??? @DMarkM1 do you know?

I need to cancel two payments made to the IRS

You'll be unable to change your payment date in Turbo Tax once you filed your return and it has been accepted but you can cancel it and then make other payment arrangements with the IRS. 

Federal income tax direct debit payments can be canceled up to 48 hours (midnight, Eastern time) before the date you designated the funds to be debited. To cancel your direct debit transaction, call (888) 353-4537 also see this link for more information: https://www.irs.gov/uac/pay-taxes-by-electronic-funds-withdrawal#errors

How do I cancel payments to the IRS

Please refer to JeanneLO's post above. Payments can be canceled up to 48 hours (midnight, Eastern time) before the date you designated the funds to be debited. To cancel your direct debit transaction, call (888) 353-4537.