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: BeZEQbbgVZcjWBaojjCUQbZhonBH
Example Output: BeZEQbgVcjWaoCUhnH

Example Input: SIxnECIKwIXLdOZgaLINOWEYzygDx
Example Output: SIxnECKwXLdOZgaNWYzyD

Example Input: QyYdHTVupfGnwJLOYhBhifYIjPSd
Example Output:
QyYdHTVupfGnwJLOhBiIjPS