Saruman’s spirit dissipated and was left impotent.
In J.R.R. Tolkien’s legendarium, after Saruman’s death, his spirit rose as a mist from his body, but then it was blown away by a strong west wind and dissipated, signifying his rejection by Valinor and his powerlessness in the afterlife. Saruman, once a Maia of Aulë named Curumo, had been corrupted by his lust for power and his dealings with the dark lord Sauron. His physical death occurred at the hands of Gríma Wormtongue outside of Bag End in the Shire, marking the end of his influence in Middle-earth.
Tolkien’s narrative suggests that Saruman, as a Maia, would not cease to exist entirely but would be reduced to a powerless, wandering spirit, unable to take part in the events of the world or return to the Undying Lands. His fall from grace was complete, and he was left as an example of the consequences of corruption and the betrayal of one’s original purpose and mission.