npm prune [[<@scope>/]<pkg>...] [--production] [--dry-run] [--json]
This command removes "extraneous" packages. If a package name is provided, then only packages matching one of the supplied names are removed.
Extraneous packages are packages that are not listed on the parent package's dependencies list.
If the --production flag is specified or the NODE_ENV environment
variable is set to production, this command will remove the packages
specified in your devDependencies. Setting --no-production will
negate NODE_ENV being set to production.
If the --dry-run flag is used then no changes will actually be made.
If the --json flag is used then the changes npm prune made (or would
have made with --dry-run) are printed as a JSON object.
In normal operation with package-locks enabled, extraneous modules are
pruned automatically when modules are installed and you'll only need
this command with the --production flag.
If you've disabled package-locks then extraneous modules will not be removed
and it's up to you to run npm prune from time-to-time to remove them.