(Quick Reference)
                delete
Purpose
Deletes a persistent instance.
Examples
def book = Book.get(1)
book.delete()
Description
The 
delete method informs the persistence context that a persistent instance should be deleted. Equivalent to the Hibernate 
delete method.
Calling delete on a transient instance will result in an error
Parameters:
- flush- If set to- truethe persistent context will be flushed resulting in the instance being deleted immediately. For example:
def book = Book.get(1)
book.delete(flush: true)