Usually the red buttons just clip out, usually by inserting a screwdriver underneath the front of the main button, and sharply levering up. This does come with a significant amount of danger though so proceed with caution... If you do get it off, it'll just push down and clip into place, remembering any springs that are under it.
Also, there's not a screw underneath the top of the cyclone is there? I've seen that before, and that's a full cyclone stripdown to get to.
Others have 2 screws on the back, then you have to unclip the front and slide it back whilst manhandling the handle. I'd need to see a picture from the top though to really know.