You can't.
If you used the wrong AGI -- or no AGI ---, your e-file be rejected. When you get the rejection notice, correct it and re-file.
https://ttlc.intuit.com/community/agi/help/where-do-i-correct-my-agi-in-turbotax-online/00/26311
I e-filed my 2019 tax return with turbo tax and was notified that was rejected twice because of no agi or wrong agi. Turbo tax suggested they would the mail in my tax return because then it would not require the agi. have not heard any response to mailing and the irs has no information. Can not find anyway what so ever to contact Turbo Tax! So what now??????????
TurboTax will not mail your return. You have to print it and mail it.
You can find the correct address to mail your Federal Tax Return by going to this site and choosing your state:
https://www.irs.gov/filing/where-to-file-paper-tax-returns-with-or-without-a-payment
Here is help for finding the address for your State Department of Revenue:
https://ttlc.intuit.com/replies/3302452
Paper-filers: The IRS asks you wait 4 weeks after you mail your return before looking up your refund at Where's My Refund?
Here is information about contacting TurboTax Customer support.
They are available from 5am to 9pm Pacific Time