Replace individual window panes with a single pane
No, you cannot remove the wood “dividers” (mullions) and install a single pane, because 1) mullions will leave a gap at sash, 2) “stop” will have gap at sash that will leak, 3) thickness of glass may need to be changed, 4) energy code requires thermal pane windows, 5) glass may need to be tempered. 

1) Those mullions are part of the sash. That is to say, the sash has a built-in reveal (at the perimeter of the sash) that creates one side of the stop. When the interior mullions are removed, you can’t just cut them off without leaving a gap. Trying to infill that gap to blend with the existing reveal will be impossible. 

2) The “stop” (probably on the exterior side of the window) will leave a gap where the mullions are removed. You’ll need new stops around the entire perimeter of the sash. 

3) Your glass is probably 1/8” thick float glass. That’s fine for small panes, but a larger glass opening will require thicker glass...probably 3/16” ...maybe 1/4”, depending where you live (wind loading requirements,etc.)

4) I don’t know where single pane glass is allowed. The energy code will require you to upgrade to double pane. This additional thickness will require a new sash. 

5) If your window is within 18” of the floor or within 12” of a door, you’ll need tempered glass. This additional thickness will not fit in the existing glass thickness space. 

If your sash has lead weights, they will need to be adjusted for the heavier glass load. 

IMHO I think it would be cheaper and better to replace the entire sash.