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: XttLMRTVbiQDKPMEXyeXPSoDGCehY
Example Output: XtLMRTVbiQDKPEyeSoGChY

Example Input: BzQaOUyLaCfWdGlaQcEAXtzDSi
Example Output: BzQaOUyLCfWdGlcEAXtDSi

Example Input: HuYHfZxsdwtzapmLmmFunDczqY
Example Output:
HuYfZxsdwtzapmLFnDcq