When you click on a Warrior in Roster Management, it prompts you to change his name.  If you press ENTER without typing a name, the warrior is completely removed from your roster.  The space is then free to sign another warrior.  It does not appear that your Reputation takes a hit for doing this.  My guess is that this is not by design.   
 
 
On a similar note, I could not find a way to abort a name change.  Perhaps pressing ENTER without typing in a name could act as the abort.
Chris