Sometimes we "accidentally" merge something that's not ready for release/qa  and need to rollback/reset/revert the commits to a cleaner state.

Here's how you can safely reset your git to previous commit:

1) find the older commit id to where you want to reset.

2) do git status to confirm there are no uncommitted changes on the current branch  

3) reset to a commit,

git reset --hard COMMIT_ID
git reset HEAD@{1}
git add .
git commit -m "reverting to commit COMMIT_ID"

4) cherry pick or patch any other commit that you like to add