git-delete-squashed-branches
Delete branches that have been "squashed-merged" into a specified branch and checkout. If no branch is specified, default to the currently checked out branch.
TLDR
Delete all branches that were "squash-merged" into the current checked out branch
$ git delete-squashed-branches
Delete all branches that were "squash-merged" into a specific branch
$ git delete-squashed-branches [branch_name]