You will have to wait until the return is either accepted or rejected by the IRS.
If the return is rejected by the IRS you can change to the standard deduction and refile your return.
If the return was accepted by the IRS then you will have to file an amended tax return using Form 1040X to change to the standard deduction.
The FAQ link below provides information on how to amend your tax return. Please note that the IRS has not released the 2018 Form 1040X. This link will be updated when the IRS has released Form 1040X.
https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed
