Paid off loan with 529 plan

Just don't enter the 1099-Q, in TurboTax.  Paying off a loan is a qualified expense, as long as the amount was $10K or less.  There is a lifetime limit of $10,000.

You can just not report the 1099-Q, at all, if your student-beneficiary has sufficient educational expenses, i to cover the distribution. When the box 1 amount on form 1099-Q is fully covered by expenses, TurboTax will enter nothing about the 1099-Q on the actual tax forms. But, it will prepare a 1099-Q worksheet for your records. You would still have to do the math to see if there were enough expenses left over for you to claim the tuition credit. You also cannot count expenses that were paid by tax free scholarships. You cannot double dip! 

On form 1099-Q, instructions to the recipient reads: "Nontaxable distributions from CESAs and QTPs are not required to be reported on your income tax return. You must determine the taxability of any distribution."