iFixit

There are several capacitors mounted to the logic board in close proximity to the power supply. Try not to disturb them, as they are delicate and may break off the board.

Grab the power supply from each side and rotate its top edge toward yourself until it clears the logic board.

Lift the power supply out of the midplane.

The power supply requires a large amount of force to remove. You may need to slightly bend the edge of the front case toward yourself for enough clearance to remove the power supply.

Disconnect the hard drive thermal sensor cable from the hard drive thermal sensor board.

During reassembly, use the tip of your spudger to plug the hard drive thermal sensor back into the socket on the hard drive thermal sensor board.