UPDATE:
(更新：)
You can add other branches to exclude like master and dev if your workflow has those as a possible ancestor.
(如果您的工作流程可能将其作为祖先，则可以添加其他分支以排除像master和dev这样的分支。)
Usually I branch off of a "sprint-start" tag and master, dev and qa are not ancestors. (通常，我从“ sprint-start”标签分支出来，而master，dev和qa不是祖先。)
First, list all branches that were merged in remote.
(首先，列出所有在远程中合并的分支。)
git branch --merged
You might see few branches you don't want to remove.
(您可能会看到几个不想删除的分支。)
we can add few arguments to skip important branches that we don't want to delete like master or a develop. (我们可以添加一些参数来跳过不想删除的重要分支，例如master或developer。)
The following command will skip master branch and anything that has dev in it. (以下命令将跳过master分支以及其中包含dev的所有内容。)
git branch --merged| egrep -v "(^*|master|dev)"
If you want to skip, you can add it to the egrep command like the following.
(如果要跳过，可以将其添加到egrep命令中，如下所示。)
The branch skip_branch_name will not be deleted. (分支skip_branch_name不会被删除。)
git branch --merged| egrep -v "(^*|master|dev|skip_branch_name)"
To delete all local branches that are already merged into the currently checked out branch:
(删除所有已经合并到当前签出分支中的本地分支：)
git branch --merged | egrep -v "(^*|master|dev)" | xargs git branch -d
You can see that master and dev are excluded in case they are an ancestor.
(您可以看到，如果master和dev是祖先，则将它们排除在外。)
You can delete a merged local branch with:
(您可以使用以下方法删除合并的本地分支：)
git branch -d branchname
If it's not merged, use:
(如果未合并，请使用：)
git branch -D branchname
To delete it from the remote in old versions of Git use:
(要在旧版Git中从远程删除它，请使用：)
git push origin :branchname
In more recent versions of Git use:
(在最新版本的Git中使用：)
git push --delete origin branchname
Once you delete the branch from the remote, you can prune to get rid of remote tracking branches with:
(从远程删除分支后，可以通过以下方法修剪掉远程跟踪分支：)
git remote prune origin
or prune individual remote tracking branches, as the other answer suggests, with:
(或如其他答案所示，修剪各个远程跟踪分支，方法是：)
git branch -dr branchname
Hope this helps.
(希望这可以帮助。)
