You can delete lifelines from UML diagrams, such as sequence or
communication diagrams, to remove an object from an interaction. When you
delete a lifeline, all send and receive messages that originate from the deleted
lifeline are also deleted. When you delete a lifeline from a sequence diagram,
all interaction fragments that cover the lifeline are deleted, but the combined
fragments and interaction uses that cover other lifelines are not.
You must have a UML diagram open that contains lifelines.
To delete a lifeline, in the diagram editor, right-click a lifeline;
then click
Delete from Model.
All send and receive
messages that originate from the deleted lifeline and all interaction fragments
that cover the lifeline are deleted. The combined fragments and interaction
uses that cover other lifelines are not deleted.