If she had no income and lived with you the entire year, then she may qualify to be claimed by you and can't file a return to claim herself. See this for whether you can claim her or not: https://blog.turbotax.intuit.com/tax-deductions-and-credits-2/family/who-can-i-claim-as-a-dependent-...
If you can't claim her because she doesn't meet these requirements, then she could write on the front of the form 1040 that she mails: "Claimed as a dependent by mistake on a non filer portal tax return."
