TurboTax does not support dual status returns. You would need to find an accountant or software that handles dual status returns.
You can file in TurboTax if you file a full year resident return. You would declare your worldwide income for the entire year and then utilize foreign tax credit to help offset any double taxation on the income from the time you left the US to December 31, 2017. If you file a full year resident return, you do not need to attach any statements.
If you file a dual-status return with an accountant, you will need to attach a statement claiming that for the remainder of the year, your tax home was in your home country (assuming you moved back to your home country) and you had a closer connection to your home country after you left. You would declare your worldwide income on the resident part of the return and only US source income for the non-resident part of the year. Dual status filers have to file as single or married filing separately and you cannot use the standard deduction.
Please see attached for more information. Publication 519 US Tax Guide for Aliens
