I want to delete all commit history but keep the code in its current state because, in my commit history, there are too many unused commits.

How can I do it?

Is there any git command can do this?

git filter-branch ?
git rebase ?
... 

My code is hosted on github.com.

Deleting the .git folder may cause problems in your git repository. If you want to delete all your commit history but keep the code in its current state, it is very safe to do it as in the following:

1. Checkout

   git checkout --orphan latest_branch

2. Add all the files

   git add -A

3. Commit the changes

   git commit -am "commit message"

4. Delete the branch

   git branch -D main

5. Rename the current branch to main

   git branch -m main

6. Finally, force update your repository

   git push -f origin main

PS: this will not keep your old commit history around