Well - *technically* you can drain the fork oil from the small 10mm drain plug on the backside of each fork lower, and pump the forks up and down to try to get out the last of the oil. In reality, unless you undo the large allen bolts up inside the bottom end of the fork legs, there is always a little bit of old oil that remains in there. I wouldn't worry about it too much if I was changing the fork oil every year and just do the 10mm nut part, but I don't change mine every year - usually every ~3 years so I end up taking the fork tubes out, etc.
That said - to get the top fork caps off, top plug removed to get oil poured in from the top, I cannot see how you can do it without at least getting the black cowling piece unbolted and lifted up&out of the way.