What?????? Why would you want to take your brake light off to put the top down???
Are you wanting to take the hard top off and you are talking about the plug on the left side? If so, that is the electrical for the rear wiper and the washer fluid line. If I remember right, there is a red slider on the plug. Slide it to the unlocked position, then give it a little tug. There is a cap on the washer fluid line to plug it closed.