Given a decent amount of self control and awareness, it's better not to block them or delete them.
They get a kick when they notice that their behaviour lead a guy to have such a hard reaction and they could even brag about it with their friends.
In my opinion unless you're the guy that feels the need to keep writing or texting (which is a huge no), the best option is simply letting them there while not interacting at all.
If they come back to fish for attention and gauge your reaction, you simply dont reply to them or you give polite short closed answers.
She "Hey X it's a lot of time since we last talked, sorry for not getting back at you but I was busy that evening"
You "all ok no worries"
Then she either doesnt write anymore cause she gets it or if she does, you dont reply or keep it close and brief again.