Is it possible to say 'where is he go to college' instead of 'where did he go to college'?
The use of 'is' should be reserved for when it's the present tense i.e. Where is he going to college? (implying you believe he's still attending college and hasn't graduated). Alternatively, you could say Where does he go to college.
The use of 'Did' is for, when you believe the college attending happened in the past i.e. Where did he go to college?