There's no way to change the date of your direct debit after you have filed your tax return. However, you can cancel the direct debit payment, then pay another way by July 15, 2020. To cancel the payment call the IRS at 888-353-4537 at least 2 business days before the scheduled payment date. See the following FAQ for more details about canceling your direct debit payment.
How do I change my payment date?
The best ways to pay would be by check or IRS Direct Pay. Go to the following link on the IRS web site for information about Direct Pay and other ways of paying your federal tax.
Paying Your Taxes