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: rvPlbIWYNYtLvgfjGXBaCgeir
Example Output: rvPlbIWYNtLgfjGXBaCei

Example Input: QuMNYgXJKXvbSqRhUHAfsIAxqUYb
Example Output: QuMNYgXJKvbSqRhUHAfsIx

Example Input: XttLMRTVbiQDKPMEXyeXPSoDGCehY
Example Output:
XtLMRTVbiQDKPEyeSoGChY