First off, are you taking regular log backups? If you're not taking those, then you can't do a restore to a point in time anyway. Determine if you need to restore to a point in time. If you do, you need to have log backups running. That will help reduce the size of the log. But, you may also need to limit the transaction size which would mean doing your deletes in smaller chunks. If you don't need to restore to a point in time, then you can go to simple recovery. You may still need to limit the transaction size though.