Remove merged local branches (git)

This command executed in in project directory with bash will delete all local branches which were already merged into master:

git branch --merged | egrep -v "(^\*|master)" | xargs git branch -d

Explanation:
git branch --merged - list all merged branches
egrep -v "(^\*|master)" - grep "master" from provided lines one by one (piped from git branch above)
xargs git branch -d - delete filtered branches (piped from egrep above)

Same sort of command in PowerShell:

git branch --merged main | ForEach-Object { if ($_  -ne '* main' -and $_ -ne '* master') { git branch -d $_.trim() } }