Planners can archive eChecksheets using the Archive icon shown on mouseover in the bottom right corner of an eChecksheet box on the Process Builder page.
Archiving hides the eChecksheet on this page and makes the eChecksheet unavailable for operator data collection.
You can view the archived eChecksheets by clicking the Show Archived Items checkbox at the top right of the Process Builder page.
Archived eChecksheets display a grey background and provide the option to restore (Unarchive) using the green restore arrow icon in the lower right corner: