If your e-filed return was set up to pay from you bank account on July 15th, the amount due will be deducted from your bank account on that date. If that is the case, TurboTax cannot change that scheduled payment. You would need to contact the Oklahoma Tax Commission using the contact information at this website to see if that is possible.
If your e-filed return indicated that you would mail a check, the instructions from the Oklahoma Tax Commission at this link instruct you to wait until you get a bill from the OTC. That bill will include a code to request a payment plan through OkTAP at this link.