All you can do is file the return, making sure that you check the Personal Interview box where it asks if the taxpayer was deceased.
If the estate was insolvent at the time of death, any outstanding tax liability just goes unpaid.
As the executor (or if acting as such), you should file a request for discharge from personal liability for tax.
An executor can make a request for
discharge from personal liability for a decedent's income, gift, and estate taxes. The request must be made after the returns for those
taxes are filed. To make the request, file Form
5495 (not in TurboTax). For this purpose, an executor is an executor or administrator that is appointed, qualified,
and acting within the United States.
