If you want to rename a branch while pointed to any branch, do:
git branch -m <oldname> <newname>

If you want to rename the current branch, you can do:
git branch -m <newname>
A way to remember this, is -m is for "move" (or mv), which is how you rename files.
src : https://stackoverflow.com/questions/6591213/how-do-i-rename-a-local-git-branch?rq=1

If you want to rename a branch while pointed to any branch, do:
git branch -m <oldname> <newname>
If you want to rename the current branch, you can do:
git branch -m <newname>
A way to remember this, is `-m` is for "move" (or `mv`), which is how you rename files.