In a sequence diagram drag an Object Lifeline shape onto the drawing page to represent an object that is destroyed during the interaction the sequence diagram represents.
Right-click the Object Lifeline shape, click Shape Display Options, and then select Destruction marker.
Note: To apply this change only to the selected shape, clear the option Apply to the same selected UML shapes in the current drawing window page in the UML Shape Display Options dialog box.
A black X appears at the end of the object's lifeline.
Indicate that an object in a sequence diagram is destroyed