See the WikiTree page links noted below on how to merge duplicate profiles of a person. If you entered BOTH people and accidentally created the duplicate you can compare the two profiles and then merge them into one.
If you see a duplicate profile in someone else's tree - you need to contact that profile manager to see if you can be added to the TRUSTED List for the ancestor to make any changes. There will be a link on the ancestors page that includes the Profile manager __________ [send private message] - click on the message part to contact them.
http://www.wikitree.com/wiki/Merging
A merge combines one profile with another. This should be done when two profiles represent the same person.
Click here to initiate a merge. If you are on the Trusted List of both profiles you will be presented with a confirmation page that enables you to choose which data to keep from which profile.