Your granddaughter would need to amend her tax return and change her dependency on the tax return. Amended tax returns, Form 1040X, can only be printed and mailed, they cannot be e-filed. The IRS will take up to 4 months to process the amended tax return.
You can complete and file your tax return with her entered as a dependent but you can only print and mail the tax return since her tax return has already been filed and accepted by the IRS with her SS number.
See this TurboTax support FAQ for the procedure to print and mail a tax return when using the online editions - https://ttlc.intuit.com/community/printing/help/how-do-i-print-and-mail-my-return-in-turbotax-online...
