"I Would make it a free day day and slay him so next time he will not be the warden"
Wrong you would tell him and all the others it is a freeday then tell him that at the end of the round he needs to switch team, If he fails to comply with these rules you would force team change to prisoners, If he changes back then you would kick him and / or say you are not aloud to be there unless you opt'out of warden and just play as guard.