Delete local and remote branches

delete-local-branches.sh

# You'll need to keep one branch.
# Specify that branch's name here.
BRANCH_TO_KEEP=master

# Switch to the branch you're keeping
git checkout ${BRANCH_TO_KEEP}

# Delete all other local branches
git branch -D $(git branch | grep -v -e ${BRANCH_TO_KEEP})

delete-remote-branches.sh

# Ensure know about all remote branches
git fetch --all

# You'll have to keep at least one branch,
# often the default branch for the repo.
# Specify that branch's name here.
BRANCH_TO_KEEP=master

# Delete remote branches whose name is not $BRANCH_TO_KEEP.
# The `sed` command is to strip the leading 'origin/' prefix
# from the branch name that `git branch -r` adds.
git push origin --delete --force $(git branch -r | grep -v -e ${BRANCH_TO_KEEP} | sed 's/origin\///')