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: uWQyOyRMKvmSdratHfTdq
Example Output: uWQyORMKvmSdratHfTq

Example Input: UdKQazyGqYGzbUzaazcJhE
Example Output:
UdKQazyGqYbcJhE