All references to a block must be erased before you can purge its block definition. 
Purge allows you to remove unused named objects from a drawing at the Command prompt. You can choose to remove nested items all at once or one level of reference at a time. If removing one level of reference at a time, repeat the command until there are no unreferenced, named objects. 
- At the Command prompt, enter PURGE. 
	 
 Options related to removing unused named objects and some empty geometric objects are displayed. 
	 
 
   
- Enter 
	 S to include or exclude nested items or orphaned data when purging all object types. 
  
 
- Enter the command line option text or select the type of objects from the list. 
  
 
- Enter the Names of the objects to purge or 
	 * to purge all of the named objects of the type selected. 
	 
Note: The PURGE command will not remove unnamed objects (zero-length geometry or empty text and mtext objects) from blocks or locked layers. 
	 
 
   
- Enter 
	 Y to verify each name to be purged.