These are all individual panes linked with the glazing bar.
Are you sure? Such a buildup would be much less rigid and thermally effective than for it to be one large sealed unit with interim spacer bars inside that make it look like several panes. Your picture doesn't seem to show any rubber seals on the glazing bar bits, which would be helpful for draught and moisture exclusion purposes
Either way, you're going to need to remove the bars to get the edge beads out, so I'd start with that. At your insistence that they're individual panes, the glazing bars will have clip on caps that need to be pulled off: place the tip of a wood chisel between the bar and the glass, at the edge so you can turn the chisel and lever against the frame rather than the glass, and gently work the bar off. If you're reusing the beads consider putting something between them and the chisel. You might also consider putting something large and relatively soft, like a bit of clean wood, between the glass and the chisel and levering on that so it spreads the load onto the glass. The main thing, to avoid glass damage is that you
don't lever the chisel so the metal of the chisel gets its pivoting support from the glass.
Once the bars are off put the chisel into the gap between the edge bead and the frame and lever the bead towards the window centre. It might help if you do the bottom bead first then you can put something on the window sill to support your levering effort. I'd say to start at the center and pop it out there unless you can tell which bead was fitted first (sometimes the corners are cut so that one is fitted before the other) - it'll either come loose and pop out or it will be stuck behind the other beads, so switch to removing those. We aware that the glass might fall out when the last bead is removed, or it may have stuck to the rubber seals in the frame and need some effort
-
The edge beads will either be a triangular shape, where one end clips into a ridge around the middle of the frame and then the edge near the room clips in after:
For this shape, when refitting, be sure you've got the center clip under the ridge in the frame and not just under the edge of the window. In the picture above the red J shape clips into the frame, it doesn't clip under the glass (yellow area/red x)
Or they will be just the hypotenuse of a triangle and clip in at only the room side of the frame. This style is a lot harder to get wrong:
If the window has been in for a long time you'd do well to replace the rubber seals too - search eBay for "bubble gasket"