I have a git commit history like this:
          U
         / 
A---B---C---D---E master
Nothing points to the commit U, but I know its hash. How can I completely remove this commit  from my repository as if it never existed? I'm the only person using this repo.
I tried using git rebase, but that can either delete parts of a branch or move commits, but doesn't seem to be able to delete a single commit.
If I do git checkout <hash> and then git reset --hard HEAD~1 I don't see the the commit anymore. Is it actually gone completely or is it still hidden in the repo?
 
     
     
    