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: pKZWKxZqQdaAHUrMTJMYiZhu
Example Output: pKZWxqQdaAHUrMTJYihu

Example Input: HuYHfZxsdwtzapmLmmFunDczqY
Example Output: HuYfZxsdwtzapmLFnDcq

Example Input: SwUTgAzgSuHxHiuLjUMlBpkqrU
Example Output:
SwUTgAzuHxiLjMlBpkqr