Using a flat edge (such as a spudger or a flathead screwdriver) pry the C-clamp from the center spindle by wedging the flat edge between the spindle and the C-clamp.

The C-clamp may pop off unexpectedly, so be careful it doesn't fall somewhere hard to reach.

The C-clamp his what holds the platter in place. With it removed, you can now et under the platter.