Can I truncate log in simple recovery mode?
You have two choices:


Break the delete into chunks, as Jonathan explained and as I blogged about here:


Break large delete operations into chunks

Give the transaction log more space to grow to accommodate the log activity (and don't shrink it after every delete; all this does is make the next delete take longer). If you run a delete command that deletes 100K rows, the log has to be able to record all of that activity, regardless of recovery model.


For a much more thorough treatment of the subject, see:


Why Does the Transaction Log Keep Growing or Run Out of Space?