Remove the last char from a string is a simple and common task, there are standard function for this, but its easy to write your own.

Method 1

 
(join "" (drop-last "hello"))
 

Method 2

 
(defn remove-last [str]
  (.substring (java.lang.String. str) 0 (- (count str) 1))
)
 
(remove-last "hello")