My w2 from a certain employer says TNNOTNEEDED IN BOX 15 and doesnt have an option for me to put in Tennessee in there at all what do I do

You can leave Box 15 blank.  Tennessee does not have a state income tax (on earned income).  There is no need to fill out Box 15.  If you have income from a state(s) other than Tennessee, you will allocate the state income in the state tax returns.  

actually leave 15-17 blank.