Remove WordPress users via WP CLI

Remove users with customer role:

# Delete user 123 and reassign posts to user 567
$ wp user delete 123 --reassign=567 --yes
Success: Removed user 123 from http://example.com

# Delete all contributors and reassign their posts to user 2
$ wp user delete $(wp user list --role=customer --field=ID) --reassign=2 --yes
Success: Removed user 813 from http://example.com
Success: Removed user 578 from http://example.com

# Delete all contributors in batches of 100 (avoid error: argument list too long: wp)
$ wp user delete $(wp user list --role=customer --field=ID | head -n 100) --reassign=567 --yes

Source: https://developer.wordpress.org/cli/commands/user/delete/