An easy way to remove it if you don't have the right tool (like me!) is to pull away the mat black cluster surround. It is clipped in and comes away with just your hands, no need for tools. This gives you clear access to the clips holding the cluster unit in and also makes it a little easier to get it out.
It's better to clip the trim back on before installing the clusters as it is a little fiddly once the cluster is in.