What are WordPress orphaned user meta and how to clean them?
User metadata is the additional information provided about each user, which is not typically stored in WordPress’s users table. Sometimes, this user metadata becomes orphaned, meaning it no longer belongs to any user. These “orphaned user meta” entries are unnecessary and should be cleaned.
To clean orphaned user meta, you can either use our Advanced Database Cleaner plugin or execute the following SQL code (used by the plugin) directly via phpMyAdmin:
DELETE FROM usermeta WHERE user_id NOT IN (SELECT ID FROM users)