Turbo tax is asking information for Box 15. My W-2 form doesn't contain information on Box 15. I cannot seem to proceed and e-file because of this. Any suggestions?

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