On my w2 on box 15 it has a State Employer ID number and state but TX is not a tax state so it doesn't show me an option in the box for that state. What should I do?

Several  states do not have a state income tax.  So these states will not show up in certain drop down lists.   Leave boxes 15, 16, and 17 blank when you enter a W-2 for these states.

Alaska, Florida, Nevada, South Dakota, Tennessee, Texas, Washington and Wyoming