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: CHIKoErswWcbipbgjjmyU
Example Output: CHIKoErswWcbipgjmyU

Example Input: wKewCMTAYgicAyjnUQXzhjthHFCe
Example Output: wKeCMTAYgicyjnUQXzhtHF

Example Input: PgnuLHMWcjJVzGyJelrh
Example Output:
PgnuLHMWcjJVzGyelrh