If you have a lot of tournaments in which this player participated, to reduce the amount of work you have to do you'll want to try to determine how many tournaments there are where the player participated as "Player A" and how many tournaments there are where the player participated as "Player B". I a situation like this, you've probably got a lot of tournaments where the player participated as "Player A", and one or a few tournaments where the player participated as "Player B". If you can determine this is the case, delete "Player B" from the database, then load up the tournament(s) where "Player B" participated. Then do as Magic_fubu said: go to the Players tab and look for the italicized "Player B" (which means the player isn't in the database, which is true because you just deleted the player from the database). Edit the player and "Merge" the player with "Player A" in the database. Then save the tournament. Repeat for each tournament in which the player was "Player B".