Stricken kin of the teen tourist fatally tossed from a Central Park horse carriage demanded Monday that the city ban the industry — saying anything less suggests his death was just “a temporary inconvenience.’’ Tragic Romanch Mahajan’s grieving family said in an emotional letter read at a vigil for him in the park that the city needs to take “immediate decisive action … to permanently phase out horse-drawn carriages before another life is lost. “The industry responsible for my nephew’s death is