disj

Disjoins an element from the set.

(disj setofelements x)

(ns clojure.examples.example
   (:gen-class))
(defn example []
   (println (disj (set '(3 2 1)) 2)))
(example)

#{1 3}

• https://www.tutorialspoint.com/clojure/clojure_disj.htm