It's cake.
You need a flathead screwdriver with a long shaft and a wire with aligator clips on each end.
Clip the screwdriver shaft to the monitor chassis with the wire and slide it under the 2nd anode cap (fancy term for the suction cup on the side of the crt) and listen for the crackle. Touch the screwdriver tip to the metal connector under the cap.
Wait five minutes and repeat. The reason for this is that sometimes the charge is unbalanced inside the CRT so you discharge it only partially. If you wait & do it again then you are just being safer. Getting zapped by one of those things hurts - just ask my wife!
When done with the second discharge attempt touch the tip of the screwdriver against the metal connector and hold it there while you peel back the cap with your fingers. Then push the connector together with the screwdriver and pop it right out of the hole in the side of the CRT.
Cake.
Don't forget there's usually a ground wire from the DAG ground (the wire that goes around the back of the CRT to drain the static from the surface) to the neck board. Sometimes these plug into the neck board, sometimes they solder to it and need to be cut so you can pull the board set all the way off the monitor
chassis.
Oh, also there may be a bead of silicone running around the CRT socket to keep the neck board on through many heat cycles. You may need to cut CAREFULLY through it with a razor knife to be able to take the neckboard off.
RJ