I don't think you have the option to control the visibility
of a button on the client. Clearly, you can set the enabled or disabled state, but to "hide" a button in the Editor you problem need to remove it on the server. Check out this article for help:
You could, of course, use Ajax to make this process seamless, but there is no pure client-side API for hiding buttons, nor is there a "hidden" button state you can set on the server.
Hopefully this helps.