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: FwkSbZVdSEKTcqFfDKxzzRi
Example Output: FwkSbZVdEKTcqfDxzRi

Example Input: ptUIcSNsiRtUWfLGkAOAf
Example Output: ptUIcSNsiRWfLGkAO

Example Input: pHAgIveCCMySyMbOvQzwZjRvQkoOci
Example Output:
pHAgIveCMySbOQzwZjRkoci

