This is completely up to you, of course, but I personally would never delete Hirds.
Why? Because Hirds not only gives your children a much higher chance to become "strong," but it also increases the chance of getting "Rowdy" children by 300%.
And unlike Warrior Culture and Coastal Warriors, Hirds gives every member of your culture +2 prowess (and +1 knights).
My point being that it is ideal for a Knight-centric run, whereas Coastal Warriors is more about MaA, and Warrior Culture is just a worse Hirds with a slightly less severe downside (-10% tech research, instead of -15%). However, I've found that you can bypass the negative modifier on the tech research by Hybridizing your culture with another.
But again, it's totally up to you (and if you're not focusing on knights, its arguably strictly worse than Coastal Warriors).