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I have the following problem - I wanted to delete some commits from my git repository history (yes, I know it's a bad habit, but I know what I'm doing). I made it using rebase (I got the instructions from there: https://ncona.com/2011/07/how-to-delete-a-commit-in-git-local-and-remote/) and the commits were removed from my remote branch, but there are still in the history (on a DETACHED_HEAD). How can I get rid of them so that they could disappear completely? Thank you for any help!

wojtek1902
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    Commits on a “detached HEAD” are only reachable by that exact certain HEAD. Once something else gets checked out, which would move the HEAD elsewhere, there’s no reference left and the commits will be practically invisible and eligible for garbage collection. – poke Sep 11 '18 at 10:03
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    You can checkout a real branch and leave the detached HEAD state. These commits will stay in the repo for a long time invisibly. In case you want them back, you can still find them by `git reflog`. – ElpieKay Sep 11 '18 at 10:03
  • @ElpieKay thank you, but I want to remove them *completely*. I don't want to find them... – wojtek1902 Sep 11 '18 at 10:07
  • Run `git prune`? – melpomene Sep 11 '18 at 10:08
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    @user2905035 See https://stackoverflow.com/questions/11271263/completely-remove-commit-from-git-database. But, unless the commits contain very big files, I don't think it's a good idea to completely remove them at once. – ElpieKay Sep 11 '18 at 10:12
  • @melpomene how to make it work with regards to remote? – wojtek1902 Sep 11 '18 at 10:13
  • @ElpieKay frankly, I don't understand how can I remove those commits from remote DETACHED_HEAD... Can you please clarify? – wojtek1902 Sep 11 '18 at 10:24
  • Possible duplicate of [Completely remove commit from git database](https://stackoverflow.com/questions/11271263/completely-remove-commit-from-git-database) – kowsky Sep 11 '18 at 10:28
  • do you have SSH access to your git server? – skyboyer Sep 11 '18 at 11:03
  • Just a note about the "practically invisible" commits. I'm staring at huge list of commits on a detached head (from a bad rebase trying to recover a PR from a deleted repo). But I'm staring at it using gitk. And they're not invisible here and it's a real headache to look at them pushing down all the correct commits and branches. Making them completely invisible, would be really nice in this case. – iJames Aug 24 '23 at 19:12

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… the commits were removed from my remote branch, but there are still in the history (on a DETACHED_HEAD). How can I get rid of them so that they could disappear completely?

The normal way of doing is to let them die by themselves. The garbage collector will eventually get rid of everything that is no longer in use. You may also manually run it with git gc.

"DETACHED HEAD" simply means that you're currently checking out any commit that is not linked to a branch name (or you checked it out using the commit SHA sum, not the branch name), implying that if you add/commit stuff from this state, the operation will occur but won't be linked to anything by default, and no branch name will be automatically updated at this stage.

If however you have a good reason to make them disappear (accidentally committed a password in human-readable form, boss bashing messages or porn pictures stored in the wrong folder), you first need to check if your commits are no longer reachable, neither from an official reference such as a tag or a branch name, nor from any other commit remaining steady, nor from any entry in the different reflogs.

So you need to clean all this out to be sure that your commit will be scavenged.

You can take a look to this entry to know what options to pass to git gc in order to enjoin it to make everything expire right now, but don't rush into it until you have completely understood what they do.

Unfortunately, you can act only on your local repository. You may use some facilities such as "push -f" to rewrite history on your remote repository if you have the right to do so. However, for janitorial operations such as gc, you'll need a direct access to the git server then operate from there.

Obsidian
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    To add a bit more: as you say, the key here is *reachability*, but for those who don't have a clear idea of what it means for a commit to be "reachable" I recommend working through the web site [Think Like (a) Git](http://think-like-a-git.net/). – torek Sep 11 '18 at 15:39