BuddyPress.org

Jeff, you are right, I wanted to change full name of the person not username. I went to the dashboard and edited his name and chose the edited name in the dropdown as well.

In site wide activitiy and in his profile there was no change, I also thought of editing the database but to be honest I was too lazy, so I just deleted him.

I was expecting an easier solution but I guess we have to do it the hard way!