Delete Users without a First and Last Name

Question

I need to clean a WordPress Web site of SPAM users. I checked the Users list and noticed that valid users have a proper Name listed; SPAM users do not have that value and a - is displayed instead. How do I delete all users with a - posted under the Name field in Wordpress Admin? Preferable, i would rather use thr MySQL Database to do this, but if it is too risky, deleting from Admin is okay, but very slow navigating through each screen, etc.

Tks for your feedback.

Answer 1

Replace the prefix in wp_users and wp_usermeta table names for the one you use.
Make backup of data from both tables before you start to delete users.

DELETE u FROM wp_users u
  LEFT JOIN wp_usermeta um1 ON u.id = um1.user_id AND um1.meta_key = 'first_name'
  LEFT JOIN wp_usermeta um2 ON u.id = um2.user_id AND um2.meta_key = 'last_name'
WHERE (um1.meta_value IS NULL OR CHAR_LENGTH(um1.meta_value) = 0)
  AND (um2.meta_value IS NULL OR CHAR_LENGTH(um2.meta_value) = 0);

DELETE um FROM wp_usermeta um
  LEFT JOIN wp_users u ON u.id = um.user_id 
WHERE u.id IS NULL;