So far I tried pressing two sides of the connector and pulling with force but it won't budge (using my fingers only). I even tried wiggling it out instead of a straight hold and pull and still no movement. I saw an old YouTube video of someone quickly pulling it out with their fingers only but they did it so fast and did not explain how they did it in the video.I don't remember a lock. Did you try pressing the button with either a pair of pliers or a flat head screwdriver while making sure the plug is pressed all the way against the horn, then pulling them apart?