At this point there is still a strip of adhesive along the bottom of the display that will hold the display to the frame like a hinge. You can loosen this adhesive by working the display up and down a few times.
Lift the display up from the frame and remove it from the iMac.
It may be necessary to slowly lift from one side to peel against the remaining adhesive.
Be very careful handling the display—it's big, heavy, and made of glass.
After the adhesive is cut, it cannot be used to re-seal the display in place. Follow this guide to replace the adhesive strips that secure the display to the rear enclosure.
The next few steps bring your hands close to the exposed face of the power supply. Do not touch the face of the power supply or any of the exposed solder. Touching it risks a high voltage shock from the many large capacitors attached to the board.
Use the tip of a spudger to push each side of the power button cable connector and gently walk it out of its socket.
When working on the power supply, be very careful not to touch the capacitor leads or any exposed solder joints on the back of the power supply. Only handle the board by the edges.