You cannot change the date in TurboTax after you have filed. You will need to call IRS e-file Payment Services at 1-888-353-4537, if this is a federal tax payment you owe. And they can assist you with changing date.
Or contact your state tax agency, if you owe a state payment. You can go here https://ttlc.intuit.com/questions/1901670 and choose your state and it will take you to their contact page with phone numbers to reach them.
