In box 15 of my w2 is says “Tn not needed” and Tennessee isn’t and option to select as state. what should i do?

Yes, Tennessee doesn't have a state income tax, so you can leave boxes 15 through 20 blank in the TurboTax program. 

Tennessee does not have a personal income tax.  Leave boxes 15 thru 17 blank (empty) on the W-2 you are entering.

The computter program needs to understand this.  Because this appears to either be a programming error, or a blatant LIE by Trubo tax.

The Tennessee Hall Income tax was repealed for tax periods that begin on January 1, 2021, or later.