I might buy this particular civic, so does anyone know how to remove this:

 

That's a Thule roof rack. You may get instructions for it, if you buy the car. It's not something Honda offered with their vehicles.

burr had a roof rack similar to that one, so you may get some information out of him.

 

There is always Google.

http://www.thuleracks.com/instructions.asp

 

Not to worry, I had one on my Old Accord and it's not bolted or anything, you will need the key to unlock the "security" covers but once they are off there are simply rings that you turn and it loosens the grip on the body of the car. Basically the rack sits on the rubber pads that are on the roof, and there are bent pieces of metal that "grab" where the roof bends in to form the area where the door meets the roof.

 

i was actually looking to buy a rack for my sedan, if you happen to sell it hit me up

 

My dad has one of those (not for a civic, but more or less the same. If it has the locking feet, then you need the key, just unlock them, loosen the feet and they'll slide off the bar with the doors open and you can pull it off. If they're non-locking feet then you can just unlock the feet and pull it off. The rack should just be clamped into the door frame.