Q:

How can I make an object disappear on the Mac? 

So basically I just want to have the user click on an NSButton, and have it disappear once it is clicked.  How can I do that? 

A:

NSButton is a sublcass of NSView, which has these two handy methods:

- (void) removeFromSuperview
- (void) setHidden:

Whichever you need depends on what exactly your application should do.