A message can destroy an object if it is the last message received by the object and you set its Action property to "Destroy".
You cannot destroy an actor or use the destroy action with a recursive message.
A destroyed object lifeline is marked by an X at the intersection point between the object lifeline and the message. The Destroy action ends both activation and object lifeline at this same point.
Note that the Destroy action does not destroy the object, but only represents this destruction in the diagram. The object lifeline ends at a precise point in time; it is not possible to graphically pull the lifeline downwards any more.
There are two possible forms of destroy messages: