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: RSIIYSRjhKYxdfDrFUukVHMOcYR
Example Output: RSIYjhKxdfDrFUukVHMOc

Example Input: sxdVYpEhCfPCWBjPvEhqYcf
Example Output: sxdVYpEhCfPWBjvqc

Example Input: PHgBWkqIkZcjMbMhNzGqExRfuK
Example Output:
PHgBWkqIZcjMbhNzGExRfuK