With the Government deferring payments until July, I'd like to reverse the payment I did on my credit card for the tax due. Is this possible?

[JeanneLO]

Only if it has not been actually paid and posted to your account. You are unable to change your payment date in TurboTax 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 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. But please wait 7-10 days after your return was accepted before calling.

https://www.irs.gov/uac/pay-taxes-by-electronic-funds-withdrawal#errors.