I would assume that if you're driving a Skyline, emissions and environmental concern may not be on your top list of priorities, especially if you're building a car for the track and race purposes. Removing this component can rarely cause a car to fail emissions testing, so I recommended keeping everything just in case in the future you need to re-install it to pass emissions testing. Removing this system doesn't harm the engine in anyway at all. Pictured below, it's the black round canister bolted to the rad support, just under the AC hard line and in front of the power steering pump.
There's one line that is connected to a hard line, that looks like a brake line, only its not. Follow this line, it will be clipped onto the frame rail, here you can cut the rubber line and route the line into a hole in the frame rail. This line is the vent for the gas emissions, so you should keep it well away from venting near the turbos, as the turbos can get very hot, you don't want to risk any sort of fire.
The picture below, has the canister removed, you can see the rubber line near the front of the frame rail that now goes into the hole at the frame. If you're curious how the engine bay looks like it's barely dirty, this was right in the middle of a major Engine Bay Clean up I did to make it shine.