An NCO does not have the ability—nor the authority—to revoke a Soldier’s smoking privileges. You do have the ability to recommend revocation of the privileges, but the decision rests with the commander.
I believe your heart is in the right place, but your actions could land you in hot water. One of the worst orders you can give is one you’re not authorized to give or cannot enforce!
Keep in mind that revoked privileges have to be related to the offense (e.g. it would be appropriate to revoke smoking privileges if the Soldier regularly throws his butts on the ground or if he was caught smoking in a no-smoking area). Let’s turn this around and say you were slightly overweight or failing your PT test and your supervisor decided to revoke your junk food & soda food privileges to whip you into shape and turn you into the lean fighting machine he thinks you should be. Think about how it would feel to have someone trample on your personal liberties like that.