newbie branch repo migration question

Hi,

Suppose I have a local repo with a branch, 'master'.  And I create a
branch based on it called, 'topic1'.  And I work and commit etc., make
changes on 'master' and merge them back and forth etc.

Now I want to move the 'master' to a remote repository, but not
'topic1', and then I want to switch 'topic1' as a branch of the remote
'master' and not the local one.  In fact, I want to 'get rid' of master
locally (or, rather, have 'master' be a tracking branch of
remotes/foo/master).

How is this accomplished?

Thanks,
David