Do you want to have your main branch named to main instead of deprecated master? Not problem at all. You should check how you named your remote repo(s), it’s usually called origin. You can check it:
git remotes
And now you are ready to go:
git branch -m master main
git push -u origin main
git push origin --delete master
Do you see this error message?
! [remote rejected] master (deletion of the current branch prohibited)
Alright, you have to set the main branch in your remote GIT repository.
And don’t forget to set the default branch in your local GIT repository:
git config --global init.defaultBranch main