We are using a branch named 'integration' as our master branch (we still have a master, but we're not using it for now) and we have a bunch of branches that have been created off it then merged back in and need to be deleted. I found this question about deleting local branches, but wasn't sure about applying the suggestions to my particular situation.
I think this will work, don't want to run this command and have it be wrong and screw up the repo.
$ git checkout integration
$ git branch -r --merged | grep -v integration| sed 's/origin//:/' | xargs -n 1 git push origin
You need to escape that /, make it ...sed 's/origin\//:/'... but otherwise, sure, that would work.
To test stuff like this, just leave the xargs part off so you see what will happen.