That's not just intake air for the engine. It also allows for COOLING air flow over the engine and then past the radiator.
They can be removed but you need to provide ample air flow for engine cooling if you do.
We've considered moving the intake screens down to the engine access doors on each lower side (we have intake screens on both sides) but have decided to instead leave them where they are and convert the area between them into a "garage" for things we won't need on a frequent basis.....welder, plasma torch, 5 gallon water jug if we have to lug fresh water rather than use a hose, the bulk of tools, etc.
Buses are built with screens high as well as low with the higher ones probably allowing less road dirt and grime into the engine bay. Our bus has high screens on both sides and the air intake down low on the right side of the engine bay with the filter being dropped down from under the bus after removing a few bolts.
Remove them if you like but don't JUST provide intake air, be sure to provide the same amount of area for cooling air in a location that will be effective in cooling the engine.