Wedge the tip of a spudger underneath each of the antenna cables, near their connectors and pry up to disconnect them from the AirPort board.

The three cables are coded with black sleeves of different lengths. During reassembly:

Connect the long-sleeved cable to the center socket.

The short-sleeved cable connects next to the screw.

The remaining cable has no sleeve, and connects in the last empty socket, next to the fan.