In this situation, I wouldnt delete their numbers as these are people you know and not been in touch in a long while. If I meet a girl on a night out, we chat, we exchange numbers (not flake cos I always make a point of ringing the number straight away whilst she is there), then we go on our separate ways. Then I fire a text the same night, the next day and no respond. Two days later, I fire another text, still no respond, then I conclude she isnt interested and Im not wasting my time and another text and she is deleted. Or I go on a date and I find that the girl is boring, and I can't see myself seeing her again or she makes it clear, she doesnt want to see me again, then her number is deleted too.
I am not into pursuing a girl who is not interested in me. Or entertaining a girl whom I am not interested in. Why waste the time and energy? But in your case, I would do the same thing and fire a general texts to girls I havent been in touch in a long while. Anyway, if she is still in my contact list, then she is there for a reason.

Good job!