removing old branches

Does it make sense to svn rm an old branch after it's merged back to the
trunk, or not? I'm thinking about doing that so only active branches are
present in my project's branches/ directory. Of course the old branch
would still be available if you knew the revision before it was deleted.
Or I could make an branches/attic directory and move it under there. Has
any best practice been developed in this area yet?

Also, does can svn switch work on a subdirectory of a WC, or only on the
whole WC?

-- 
see shy jo