When using UOM is it possible to hide "Selection" dropdown?

It is not possible to hide the "Selection" dropdown from the UOM Pricing engine. The Quantity and Selection in UOM pricing engine work together to get the correct pricing. If you are selling the product with single UOM quantity and do not want the "selection" option to show then you can create a simple quantity based Calculator pricing Engine that will allow the user to only select the quantity. You can add the text to the quantity field to display that it is a UOM and they are actually selecting the number of Boxes when they choose the quantity in the pricing engine.