How do I get "Inkball" out of the Registry?

I deleted Inkball sometime ago, but cannot get the Inkball references
out of my registry. I've right clicked on Permissions, then tried to
give full control to my user-ID, full control to Administrator (Me),
and I've tried to create a new Everyone user who has full control.
Everything I've done has been denied. I know this is trivial, but I
would like to understand why I can't get rid of this item!

Thanks, Bill