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.

XjRLBIuGSzGcqVUCMPmbiFBnjKR
XjRLBIuGSzcqVUCMPmbiFnK

wAsRjpOXVvfYfdiZmFYrqi
wAsRjpOXVvfYdiZmFrq

vSdLBugCbKUwEzgkOnVZvyGCRdrwlq

vSdLBugCbKUwEzkOnVZyGRrlq