In The Matrix Reloaded, after shooting one of two werewolves in the Merovingian's chateau, why does Persephone let the other one escape and tell the Merovingian what's going on, instead of deleting him, too?
Persephone was only helping Neo and company as a means to betray the Merovingian, in return for his betrayal of her by having sex with the woman who ate the cake in the restaurant. It would defeat the purpose of her betrayal to help Neo rescue the Keymaker without the Merovingian finding out that she betrayed him, so she wanted the other werewolf to run and tell the Merovingian what she did.
Persephone reveals why she betrayed the Merovingian when the Merovingian found Neo and company with her and the Keymaker:
Merovingian: Oh God, my God, Persephone how could you do this, you betrayed me [speaking French]!
Persephone: Cause and effect, my love.
Merovingian: Cause? There is no cause for this, what cause?
Persephone: What cause? How about the lipstick you’re still wearing?
Merovingian: Lipstick? Lipstick? What craziness you are talking about woman, there is no lipstick.
Persephone: She wasn’t kissing your face, my love.
Merovingian: Ai-ai-ai-ai-ai-ai, woman, this is nothing, c’est rien, c’est rien du tout. It’s a game, it is only a game.
Persephone: So is this. Have fun.
That's why she not only told the werewolf to go and tell the Merovingian what she had done, but that he'd be in the ladies' room (where he was betraying her just as she was betraying him):
You can either run to the restaurant and tell my husband what I have done, or you can stay there and die.
He’s in the ladies’ room.