iFixit

Remove the two 4.8 mm T6 Torx screws securing the display data cable to the logic board.

Grab the display data cable connector by its black tab and pull it straight up off the logic board.

Inverter cable on 24inch iMac pulls off to the left.

Pull the inverter cable connector straight up off its socket on the logic board.

Peel back the aluminum EMI tape from the two vertical edges of the display.

During reassembly, it is helpful to use several small strips of tape to hold the EMI shielding along the left and right edges of the display footprint out of the way before lowering the display into the rear case of your iMac.

Allow the EMI shield to hang down from the display.

Remove the four 8 mm with 2 mm thick head coarse-thread T10 Torx screws securing the display to the rear case.

These screws are recessed, so a thin screwdriver such as this is essential for removal. Bit drivers tend to be too short for this application.

It is strongly recommended to use a magnetized screwdriver so the screws won't fall into the iMac.

Lift the display from its lower edge and pull it toward yourself to peel off the EMI shield attached to its top edge.

Be mindful of any cables that may get caught during removal.