You can't kill someone who was never born. 
I have no problem with eliminating a murder before they were born. So what that things may be affected going forward. It's the new timeline. I don't understand why Barry felt compelled to tell Diggle he had a daughter instead of the current son. It's not like he lost his daughter. He never had one and he had no memory of having one. If he's happy that he has a son, why would that change?
Whoever has the time travel technology if they are altering history to prevent creating a killer is TimeTraveller Victorious.

I have no problem with eliminating a murder before they were born. So what that things may be affected going forward. It's the new timeline. I don't understand why Barry felt compelled to tell Diggle he had a daughter instead of the current son. It's not like he lost his daughter. He never had one and he had no memory of having one. If he's happy that he has a son, why would that change?
Whoever has the time travel technology if they are altering history to prevent creating a killer is TimeTraveller Victorious.
