Thanks man, appreciate it. I wanted usern, passwd, id, auth to be checked for duplicated so I added auth:
DELETE logs
FROM logs
INNER JOIN
(
SELECT
number
, @seq := IF(CONCAT(usern, passwd, id, auth)<>@prevvals, 1, @seq+1) as seq
, @prevvals := CONCAT(usern, passwd, id, auth) as prev
FROM logs
JOIN (SELECT @prevvals:=null, @seq:=0) as init
ORDER BY usern, passwd, id, auth, date DESC
) as count USING (number)
WHERE seq > 1;
Although it gave the error: #1054 - Unknown column 'number' in 'field list'
Number field looks like this: