First of all BOTH voltage and amperage can kill you, but yes, with the same voltage at different amperages, the higher amp will kill you faster/be more painful.
That said I'll start with my usual discussion:
In general, unless you are working on the chassis (e.g. soldering) or swapping a tube and are not doing stuff with the monitor on, you DO NOT NEED TO REMOVE THE ANODE WIRE OR WORRY ABOUT THE 30,000 volts that stored in the tube. In these cases doing any of this is not necessary.
What you DO need to worry about is the risk that you can implode the tube by improper handling when attempting to remove the monitor from the cabinet. a 19" monitor will weigh 50 # or so, and has a center of gravity very very close to the front (like a couple inches in) due to the very thick front glass on the tube. When removing you need to make sure it doesn't tip down or tip up or swing it from side to side as you pull it out. Doing so would probably send the neckboard or neck itself crashing into the side of the cabinet and then breaking the tube, hopefully only destroying the vacuum in it, or worst case, imploding the tube causing a shattering of glass up to 20 feet away (and directly into the chest/face of the person removing it.)
Okay, that said, remove hte wing nuts while having someone hold the entire frame of the monitor. You don't know if it will release and fall or if it will simply rest without the wing nuts in place. Slide it off straight forward at the same angle to the floor it is at (e.g. slightly lifting it it looks like).
Be careful of attached wires to the board. There should be 3 wires:
Double AC wire, typically black, around 16 gauge
Ground wire, typically yellow or green, either 16 gauge or a flat metal ribbon covered in plastic
A bundle of up to 6 wires leading to plastic connectors on the board. These are the video signals.
Once out you will probably want to place it on a table as high as the control panel and see if you can leave it plugged in so you can work on it without adjusting, then remounting, then removing, re-adjusting,etc..
That looks to me like a Hantarex 9000 monitor. It is SUPPOSED to have a remote PC board with about 10 wires leading out to it. Have you checked inside the coin door, or under the control panel for any such board? It should have about 7 or so mini potentiometers on it attached to a rainbow cable of wires twisted into a round bundle. I would doubt they would have left the remote attached directly to the board (it can go either on board or on a cable extension on this model) if in fact the back door is not removable (which surprises me as well)
I have one of these monitors (if it is the 9000 which it looks like) at home and could take pictures of the controls and board and upload them this evening when I'm home.
No, the control for VPOS is NOT the blue thing. And no, VPOS is not on the neck board. The only things ever on a neck board are gun/grid controls such as the brightness level of RGB (Drive), the cutoff of RGB, and sometimes screen and focus grid controls.
The vertical/horizontal controls will be on the main chassis where the circuits are to control the yoke are located.