You cannot turn it off. You can set the recovery mode to simple (truncate on checkpoint in SQL7). It will still log everything but completed transactions are not saved. You still have to have enough room for your normal operations, big enough to handle your largest transaction.
If it just deletes that are causing a problem, try using truncate table instead of delete. Much faster and a lot few log entries.
Andy
http://www.sqlservercentral.com/columnists/awarren/