How would you clean up unused side-branches in your commit trees (not real git branches)?
Example (tree, fake-commit-hash, commit message, optional [pointers]):
* 0001 last commit [master] [origin/master] [HEAD]
| * 0002 old, unused merge
|/|
* | 0003 some remote commits
* | 0004 another commit from remote
| * 0005 old, unused commits
|/
* 0006 old tree
The path 0001, 0003, 0004, 0006 should stay untouched, but the commits 0002 and 0005 are not useful and aren't doing any good. How do you delete the commits 0002 and 0005?