Can you voluntarily choose to have one trooper leave a fireteam by spending an order on them, or do you have to break the fireteam entirely? Additionally, can you spend an order on a member in a fireteam to put them in suppression? Would that make them the fireteam leader and subsequently break the fireteam as you can't be in suppression and in a fireteam?
You can't just drop someone from a fireteam. The only ways someone leaves is listed in the Fireteam Integrity rules For suppression it depends which type of order you spend. A regular or tac aware order will make them the leader and then break the fireteam.