In this task, you are given a string of characters. You need to remove duplicate characters from the string if any, and return the resulting string.

Example Input: sZSPsCZeZilgLkWQtnAsec
Example Output: sZSPCeilgLkWQtnAc

Example Input: ZJRrdhPmcXwKgJTuvFEEpLx
Example Output: ZJRrdhPmcXwKgTuvFEpLx

Example Input: pRLRjmBQYxfuPuhnIiWinXvZknIW
Example Output:
pRLjmBQYxfuPhnIiWXvZk