How do I reduce Working Panel Width???

I just had the same issue. Pull the individual groups of tabs (characters / paragraph) (swatches / color / gradient) out of the stack and then put them back together one group at a time. I did this initially to try to find the culprit – which was the widest. I didn't notice any tab being forced at that larger width, they all seemed to be more narrow when pulled apart. 

But here is the fix: Drag each little group over the left and let it float. Then close out any individual tabs that you don't use (for me it was things like "CC Libaries", "Comments"). Then start putting the tab groups back together in a stack, one group at a time. To do this you drag them each over until you see a blue overlay line. First you'll see a vertical blue line to attach the first group in a stack next to the far right stack ("Properties" for you). Then as you drag the next groups you'll see a little horizontal line to nest them under one another. You should notice by now the stack is back to its standard narrower width. Good luck!

Are you clicking the small double arrows at the top of the palettes? Those will collapse the panels into vertical rows of icons. You can also change from the default Essentials workspace to another kind of workspace by going to the Window menu and selecting the Workspace fly-out menu. Workspaces can be modified to varying degrees too.