Removing Sleeves from Bar

I’ve got a cheap $50 bar, and I’m trying to figure out how I remove the sleeves (I’m assuming they’re removable.) I take out a small screw with an allen wrench to get out the little cap at the end, but then I encounter a 10mm bolt that is next to impossible to loosen. I’d like to get the sleeves off to clean the thing and make sure that it’s well-oiled, but right now this seems just about impossible. Have any of y’all done this before, or do you have any suggestions as to how I would go about doing this?