Did this plan cover you or other family members as well? If so, then you will enter the 1095-A as is and select that you shared this plan with someone who is not on your tax return if you are not claiming him this year. You can choose to allocate 0-100% with your son claiming the other portion.
Your son will need to enter the 1095 A on his return as well, even if you choose to allocate 100% to yourself.
If this plan did not cover anyone but your son and is in your sons name but you are claiming him, then you will still need to enter this on your return.
If this plan did not cover anyone but your son and is in your sons name, then you will do nothing with it on your return. He will enter it on his return.