You don't exactly "deduct" it; you enter the 529 distribution in the Education section, and then claim the tuition, fees, and room and board.
First enter the 1099-Q (for the 529 distribution) in:
Deductions & Credits > Education > ESA and 529 qualified tuition programs (from 1099-Q)
Then enter the qualified educational expenses:
Deductions & Credits > Education > Expenses and Scholarships (Form 1098-T)
This will offset your qualified distribution from a 529.
