All you have to do is remove the two bolts on both sides underneath the trunk lid. Then cut the wiring that is attached to the spoiler. Make sure to leave enough slack in case you want to reinstall the spoiler. I recommend covering the ends of the wires with at least electrical tape to prevent any possible shorts. You are now ready to install another spoiler/wing...simple.
the harness is just a regular harness, just unplug it. it's on the passenger side of the hatch. if i remember you gotta remove the black panel that covers the underside of the hatch. you can't miss it.
just know there will be 3 holes on each side and you will need to get 1 of them filled on each side and the hatch repainted if youre planning on running a type R spoiler. or at least plug them if youre on a budget.