I've recently been having a problem where an area will stay lit after I take down any and all torches found there. When this used to happen I could just put up the torch and take it down again and it would correct itself, but now that just makes it worse. I have found that flooding the area with water will fix it, but that is not an option with a specific area I have.
So I guess I'm just looking for advice to make something dark again.
Try breaking the block the torch was on, that should stop at the very least that torch's light radius, and when I do that sometimes it stops all the fake illuminations, which for me do not happen often. sounds like you have a crap internet connection.