Having a W isn't the most ideal. But, the way I look at it, there's two possibilities if you don't drop it. Either you have enough time for this class and do well, and all is peachy. But, if you don't have the time currently to put effort into this class and do poorly, then that's another bad grade that'll count toward your GPA.
W's don't count toward your GPA. They aren't great to have, but having one won't hurt you as much as something like an F. And for a class that isn't required, it's something that gives pause.
I applied with two W's and an average-ish (3.5) UG GPA. My W's were due to a bout with serious illness, but I opted not to explain them. Maybe I would if there was a pattern of behavior, like multiple withdrawals or a semester where I withdrew from all my classes though. One W though? The admissions teams at your schools would better be able to say, but I find it hard to believe one W is going to be this massive red flag that makes an admissions team reconsider you.
It sounds like you've thought about where your limits are. We only have so much time in they day. Decide how much time this class needs, and assess whether you have time to dedicate that between all your obligations. If you can do it, definitely do it and give it your best because that option (getting a good grade and sticking with it when things are difficult) IS probably better than withdrawing. But if you have so many things that you aren't sure you can do the work needed, withdrawing may be the best option you have.
