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: ngGDcYbncvLyDvYspBnpiSDhWKg
Example Output: ngGDcYbvLyspBiShWK

Example Input: vSdLBugCbKUwEzgkOnVZvyGCRdrwlq
Example Output: vSdLBugCbKUwEzkOnVZyGRrlq

Example Input: OIrNYBqClnipsOAEbYYImPKkBDq
Example Output:
OIrNYBqClnipsAEbmPKkD