I have a 1 acre area of soil in Upstate NY, The soil has been disturbed from construction, and its full of rocks. How do i clean them and prepare them to grow a lawn/grass.
Depends on what you really have, soil-wise, what want to do with it and how you will do that.
Bury it in 3-6" of topsoil is a perfectly normal option - not one I usually reach for, but common enough, and it solves the rock problem without having to move any of them, since rocks down in the roots of a lawn are just fine. If what you have is basically subsoil, rather than abused topsoil, hauling topsoil in is certainly the quick and easy way to fix it, if you can stand the price.
If there's some approximation of topsoil there, but things are mucked up from construction, you might be able to rake the rocks, till and rake more rocks, and plant grass or lay sod. Aside from the "screening buckets" there are also "power rakes" that have teeth attached to a rotating cylinder which will rake rocks out and make a seedbed, and York rakes that are like a large tractor-pulled hand rake.
Otherwise for almost any option that involves growing things, you may need to commit to a while growing other things to build some soil to work with; and you will probably want to remove most of the rocks, via some mechanical means. "Green manure" crops such as buckwheat or vetch in spring/summer and winter rye (not ryegrass - rye, the grain crop) in the fall, tilled in before they make seeds and become weeds in their own right are typical on-site soil-building methods - hauling in other types of manure or compost will also be beneficial. The roots help to loosen the soil, and the green material of the tops helps to make humus as it breaks down. That will greatly improve the stand of grass you get after a year or so of building the soil, .vs. trying to seed a batch into poor soil directly.
You should also do soil testing to see if you should apply lime (and perhaps gain some insight as to how much help your soil needs more generally.)
There's a device that attaches to heavy equipment like a skid steer called a screening bucket that will screen out rocks from dirt. For such a large area that's probably your best option.
You take a bucket full from the ground, the soil drops out, the rocks remain and you dump them somewhere else. The come in different designs but here's a video of one to give you an idea. https://youtu.be/eKvrc5NDlj4
Doing it by hand with a soil sifter shovel fulls at a time would be too much work and take a lot of time. If it's only on the surface though, maybe you can just rake them away using a bow rake or large landscaping rake. There's probably heavy equipment that can rake it up too.