You probably don’t need this command.

From the help:

In most cases, users should run git gc, which calls git prune.

If you want to know how clean-up references to remote-tracking branches, see the Prune branches page.

Tutorial

See git prune tutorial in the Atlassian docs.

The git prune command is an internal housekeeping utility that cleans up unreachable or “orphaned” Git objects.

Unreachable objects are those that are inaccessible by any refs.

Any commit that cannot be accessed through a branch or tag is considered unreachable. git prune is generally not executed directly. Prune is considered a garbage collection command and is a child command of the git gc command.

The git prune command is intended to be invoked as a child command to git gc. It is highly unlikely you will ever need to invoke git prune in a day to day software engineering capacity. Other commands are needed to understand the effects of git prune.

Help

git prune [-n] [-v] [--progress] [--expire <time>] [--] [<head>...]

Examples

$ git prune --dry-run --verbose

$ git prune --dry-run --verbose --expire=now

Delete branches which have been deleted on the GitHub remote.

$ git prune remote origin