Writing portion for ACT

What will happen if I signed my son up for the writing portion for the ACT and he decided not to do it when he was there? Will this hurt his score?

You should contact ACT in advance to change your son’s registration to not include the exam. If he decides not to take the writing portion on the day-of, he should let the test center know as soon as he arrives. You may be eligible for a refund. According to the ACT website:

Test Option Change – Before the late registration deadline, you can add the writing option, if a seat is available. After the late registration deadline, you can only remove the writing option. If you decide to not take the writing test on the day of the test event, you must contact ACT in order to receive a refund.