It's recommended that old archived/unpublished content be removed using the Drop Old Asset Versions feature on the Backend Maintenance page.
However individual contentlets can also be deleted by copying and pasting the contentlet identifier (as seen as the top field when editing a contentlet) into the Delete Contentlet box and clicking the “Execute” button.
To delete multiple contentlets at once, enter a comma separated list of contentlet identifiers into the box.
Example: 6e37bf99-1c98-4033-b8ff-f6c0e47877f5, e075d0b3-4fc5-4f3a-852a-66d8417c66f3, 2914eedb-0f73-4142-b91b-bc55282f09ac
