I did a post on this earlier (I’ll link it once it’s uploaded, perhaps), but it relied on me being in a Unix-like system. Because I do Windows development right now, I wanted a way to easily do this in PowerShell. StackOverflow certainly has answers, but I cobbled together my own version below that works for the toolkit I have.
git branch --merged | rg -v "(^\*|master)" | %{ git branch -d $_.trim() }ripgrep has been in my toolkit for years now at this point, so I used it for filtering out master. The last piped part is strictly used in PowerShell and was the part I was missing, since I was used to using xargs before. Tada! Works like magic.