Hello, My name is Steven i have recently started breeding budgies and am very new to it.?

I have only a small aviary with 19 birds, i have put 4 nest boxes in the inside part of the aviary and one of my hen birds started going inside one of them. She then laid 4 eggs 2 of the eggs have hatched on the correct dates to two very healthy chicks while the other two have gone over their dates by a few days so i am now believing that they are infertile the question i would like to know is when should i take the infertile eggs away or should i even leave them there ? Any Help Would be greatly appreciated. :)