Yes, you should disconnect both the remote board for the monitor, and the jamma harness which is also connect to the monitor. Lie the cab on its back, take off those 4 bolts (which connect to the frame, not the ones connected to the monitor!) lift half way out, turn and put back down. Reconnect everything. Make sure you turn the correct way for vertical games (which is counter clockwise).
BTW: those bolts that are closer to the monitor corners (which were circled in the above pic) are used when the monitor's frame does not sit perfectly on the cab's mounting points. While the cab is on its back, you just loosen these bolts, to reposition the FRAME (not tube) over the mounting points (very carefully!) then retighten. You almost never need to do this, unless you had replaced the tube/frame and need to realign.