Just call them, explain the situation, be sure you can pay it in full now, and offer to do so. Ask if they’ll still delete after payment.
Your score only increased a few points from the other two coming off because after they were gone, you still had a derog. Works the same in reverse - the first set of to hit a clean report murders your score. Additional ones do much less damage. The point loss is because any derog exists, not so much how many exist.