Buy Only Selected Products

Does nopcommerce support only selected products buy or customer must buy all products in cart?

The customer must buy all products in cart.  They can remove items from the cart before checkout.

I am developer, I can modify source code but I do not have any idea about checkout logic. Anyone have an idea how can i do that?

Do what?  Have the cart have a checkbox next to each item to indicate which ones to checkout with, and still leave the other items in the cart?   (It may be easier to change the 'remove' checkbox / 'update shopping cart' button to "Move" the items to the Wishlist.)