Archiving an item (page or asset) in CM1 means it is removed from the Live server and no longer viewable by the public. This is also referred to as "Unpublishing" or "Removing from Site". The item, however, still exists in CM1 in the Archive state, and can still be edited and republished at a later time. (Learn more about Workflow states.)
IMPORTANT! You should archive/unpublish pages and assets BEFORE deleting them in CM1. Deleting an item in CM1 may not automatically remove it from the Live server and may still be seen by the public and found by search engines.