Help deleting old data clogging up database (Reality)

[DangerRuss]

Im trying to delete old survivor ID's that are dead and also trying to clean up the old log_entry stuff but the query's Im using don't seem to work. I tried

DELETE FROM survivor
WHERE is_dead = 1;

but that yells at me because it won't delete survivor id's that reference instance_deployable id's... so I tried this

DELETE FROM survivor
WHERE is_dead = 1
AND id NOT IN (
SELECT owner_id FROM instance_deployable
);

which just doesn't work at all.
I also tried this

DELETE FROM `log_entry` WHERE `created` <= date_sub(now(), INTERVAL 1 DAY)

and that didn't work. HELP lol