WHERE col1 BETWEEN TIMESTAMP(CURRENT DATE - 1 DAY,6) AND
TIMESTAMP(CURRENT DATE ,6) - 1 MICROSECOND
This will always delete all of yesterday's data no matter in which hour you run.
As Larry mentioned there are several ways.
1.You could DELETE rows using DATE function. WHERE DATE(TIMESTAMP) = CURRENT DATE - 1 DAY
2. Another method REORG DISCARD. During the DISCARD you could save DISCARDED rows in the file. To discard rows we could use below cretiria.
WHEN DATE(TIMESTAMP) = CURRENT DATE - 1 DAY