SHELL

git change master to main

# Step 1 
# create main branch locally, taking the history from master
git branch -m master main
# Step 2 
# push the new local main branch to the remote repo (GitHub) 
git push -u origin main
# Step 3
# switch the current HEAD to the main branch
git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/main
# Step 4
# change the default branch on GitHub to main
# https://docs.github.com/en/github/administering-a-repository/setting-the-default-branch
# Step 5
# delete the master branch on the remote
git push origin --delete master

Git change branch from branch to main

git checkout master        # to be sure you are on master branch
git push origin HEAD:main  # and then push the current branch (as master) to main

change master to main git

$ git branch -m master main