You are unable to remove your dependant information or tuition transfer by "unchecking" a box in TurboTax. You'll need to "edit" the information regarding that dependant first, then return to your profile and "delete
that dependant.
Start by going to Deductions > Additional Dependant Information. Then make sure you have a checkmark beside any claims you may be making for this particular dependant, and continue to the appropriate section and make the edits there.