You can use hg commit --close-branch to mark a branch as closed:
http://www.selenic.com/mercurial/hg.1.html#commit
Closed branches will not show up in hg branches or hg heads by default (only if the -c/--closed option is specified), so I'm not sure how you're seeing "clutter"?
What exactly would you gain by merging things?
Amber
2010-09-03 19:36:01