In general:
1. Unplug the video signal cable, the power cord, and detach the frame ground wire (if present).
2. If this is a universal frame monitor then there are 3 screws at the top and 3 screws at the bottom of the front frame. Monitor should carefully tip out of the front of the game.
3. HAVE A HELPER LIFT IT OUT. Don't break the neck of the picture tube.