This bug has actually been there since version 2.0, but changes in 2.6 beta 2 exposed it. Finally. When you delete a player, the player is first removed from the database, then removed from any leagues, then the screen is updated. The bug prevented the player from being removed from any leagues (it was a bug, but didn't produce an error, and since the player is no longer in the database, the fact that internally he was still part of a league isn't exposed, so no one would ever notice). A change in 2.6 beta 2 made this bug actually an error.
So, for 2.6 beta 2, consider it an annoyance, because it's still doing the same thing it always has done: it deletes the player, but internally the league still thinks the non-existent player is part of the league. It just doesn't update the screen, so you'll have to leave the tab and re-enter to update the player list. I would simply tap ESC twice to close then open the Settings dialog.