Normally Google Chrome is very good at allowing you to close misbehaving tabs. Each tab is like its own little universe so if it crashes it doesn't affect other tabs. That's the whole "multi process" thing that Chrome brought to the WebKit party and was part of the reason for the Blink break-up.
But let's say there is a tab that just won't close. You click the closing ✕ and nothing happens. Try using ⌘W to close it, nothing. File > Close Tab, nothing.
It happens to me maybe once a week as I'm browsing around different Pens on CodePen. Perhaps there is an infinite-loop in the JS or some other madness and the tab just won't crash, it just hangs.
You can get that tab closed by using the Task Manager.
Find the tab in the list. They are listed by <title> so hopefully you either recognize it or can drag the window wide enough to see the name in the tab itself. Then click the End Process button in the lower right. That'll close that tab no matter how stubborn it's being (in my experience).