(remove-ns sym)
Removes the namespace named by the symbol. Use with caution. Cannot be used to remove the clojure namespace.
;; Let's create a namespace and then remove it
user=> (create-ns 'my-new-namespace)
#<Namespace my-new-namespace>
;; removing a namespace will give you the namespace you just deleted, if one existed
user=> (remove-ns 'my-new-namespace)
#<Namespace my-new-namespace>
;; removing a namespace that does not exist, will tell you that nothing was removed,
;; by returning nil, and won't give any errors
user=> (remove-ns 'my-new-namespace)
nil