Deleting requirements destroys them permanently. Sometimes it is preferable to mark requirements as obsolete. Obsolete requirements can be hidden, shown, and recovered.
To mark a requirement as obsolete:
 (Delete) in the toolbar or right-click the requirement and click 
                     			 Delete. 
                     		   
                  		   A dialog box appears.
 (Delete) in the toolbar or right-click the requirement and click 
                     			 Delete. 
                     		   
                  		   A dialog box appears. 
                  		   
                  		
               To show obsolete requirements, right-click any requirement in the Requirements tree and click Show Obsolete Requirements.
To hide obsolete requirements, right-click any requirement in the Requirements tree and click Hide Obsolete Requirements.