Resurrecting an old thread when I did a Google search on how to remove/disconnect the third brake light in the rear window after having the spoiler installed.
I have a 2015 Altima SL and finally purchased the OEM rear decklid spoiler. I got it on sale from Nissan's eStore for $292. I don't do aftermarket knock-off spoilers. They are cheap for a reason. They are not made to OEM standards so they do not always fit properly, the paint is done cheap so it typically does not last, and sometimes does not match the OEM paint. The LED brake light in an aftermarket spoiler is typically a cheap part that will either burn out prematurely, or the LED lamps will lose their brightness and barely light up after a few months or years. They usually never include the factory connector to plug into the factory harness for the LED brake light, which means you have to cut into the factory wiring. But if you only spend $100, you get what you pay for. I would rather have the spoiler last the lifetime of the vehicle. I got lucky too...my dealer is so good, they only charged me $57 to install the spoiler. He gave me a deal and only charged me for 30 minutes of labor when the spoiler is typically one hour. With drilling, sealing, rust protection, wiring, adhesive...I would rather leave that up to the experts since they install spoilers all the time on vehicles.
So back to the topic at hand...the high mount brake light in the rear window. According to the OEM installation instructions for the rear decklid spoiler, Nissan leaves the rear window brake light plugged in, even though the spoiler includes the integrated LED brake light to replace the rear window brake light. FYI, as stated by others, the rear window brake light is an LED assembly with four LED lamps inside. There are no bulbs to remove, but very easy to unplug. The OEM spoiler plugs into an existing factory connector underneath the interior trim cover in the truck lid. So you can unplug the rear window brake light without affecting the LED brake light in the spoiler. In my opinion, the rear window brake light should be disconnected when the rear spoiler with integrated LED brake light is installed. It looks totally stupid, and cheap, when the rear window brake light is connected with the spoiler installed. It screams out, "I installed an aftermarket spoiler and hacked in the brake light to make it work...so that is why my rear window light is still plugged in". I don't know why Nissan leaves it plugged in when other vehicle manufacturers disconnect the rear window brake light when the spoiler includes the integrated LED brake light. When I had a 2003 Accord Coupe, the OEM spoiler with integrated LED brake light actually plugged into the rear window brake light harness (disconnecting from the light bulb portion of the harness), forcing you to disconnect the rear window brake light. So whenever you saw an Accord Coupe from the 2003 to 2007 era with both rear window brake light and spoiler brake light illuminating, you knew they had a cheap aftermarket spoiler installed. It makes the car look cheap when both light up.
The rear window brake light is very easy to disconnect. Get into the back seat and push on the brake light housing with your two thumbs close to the rear deck, pushing towards the rear window. You will release the two tabs on the back of the brake light housing and it should pop up. Then you can pull it towards you, unhooking the two tab hooks close to the rear window glass. Pull up on the wiring from the rear deck and you will expose a harness connector. Unplug the rear brake light from this harness connector. You cannot unplug it from the LED assembly underneath the housing. It might look like a plug, but it appears to be a permanent connection at that point. I wrapped the exposed plastic plug with rubber tape so it would not rattle against the housing. I also covered both exposed connectors with electrical tape. Then I taped both wires together with electrical tape so neither connector would rattle in the rear deck, but they remain unplugged. Snap the brake light housing back into place and you are done. The LED in the spoiler will light up, but the rear window light will remain dark. Most people have tinted windows anyway, so the housing is not visible. Now the car won't look cheap with two high step mount brake lights. Before and after pics are included.