[plt-scheme] uninstalling .plt packages in 299

In the past, when I've wanted to uninstall a .plt package that I had 
installed, I found the directory in my local collects library and 
deleted it. Now in v299 I see there's an info-domain collect with some 
sort of package registry, so I'm not sure I should do that.

a) How do I uninstall such a package?
b) Is there an automated "remove package" functionality akin to Windows' 
"Add/Remove Programs" control panel?
c) Comment: it would be good to have the option of undoing the 
installation of a .plt package upon failure.

Dave