Hey Sid I thought you were displaying.
Its generally SELECT DISTINCT all over.. Anyway,
What you can try is with sub queries in HANA SQL making use of ROW ID's. I have just tested the one below and it seems to give results.
DELETE FROM "Schema"."TEMP"
WHERE "$rowid$" NOT IN (SELECT id FROM (SELECT DISTINCT customer,MAX("$rowid$") as id FROM "Schema"."TEMP"
GROUP BY customer))
Check if this helps.
Caution : Make sure ur AUTO COMMIT is off. Try first with a temporary table .Play safe with delete 
Regards
Avinash Raju