Remove non-public user data from standard WP database.

wp-anonomize-user-data.sql

-- generic email addresses and new passwords for users

UPDATE wp_users
SET user_email = CONCAT(user_login, '@example.com'),
user_pass = MD5(CONCAT(RAND(), CAST(ID AS CHAR), user_login));

-- generic email addresses for commentors

UPDATE wp_comments
SET comment_author_email = CONCAT(CAST(comment_ID AS CHAR), '@example.com');

-- admin email address

UPDATE wp_options
SET option_value = 'admin@example.com'
WHERE option_name = 'admin_email';