prune_branches.sh

#!/bin/bash

# This has to be run from develop (NOTE: if master is your main dev branch, edit the file.)
git checkout develop

# Update our list of remotes
git fetch
git remote prune origin

# Remove local fully merged branches
git branch --merged develop | grep -v 'develop$' | grep -v 'release/' | xargs git branch -d

# Show remote fully merged branches
echo "The following remote branches are fully merged and will be removed:"
git branch -r --merged develop | sed 's/ *origin\///' | grep -v 'develop$' | grep -v 'release/'

read -p "Continue (y/n)? "
if [ "$REPLY" == "y" ]
then
   # Remove remote fully merged branches
   git branch -r --merged develop | sed 's/ *origin\///' \
             | grep -v 'develop$' | grep -v 'release/' | xargs -I% git push origin :%
   echo "Done!"
   say "Obsolete branches are removed"
fi

echo "Please, tell your teammates to run 'git remote prune origin' command in order to clean their local repository"