Hovering your cursor over the list of groups, actions, and emails on your dashboard; the list of actions, emails, and reports on a group's manage page; or the list of uploads for yourself or your groups will show a hide icon. Click that icon to hide that item from your view and the view of others.
Hidden items will not be available for selection and will not show up in lists of similar items. For example, hidden groups will not show up on your dashboard or be available as an option for sponsoring pages. Hidden actions will not show up in your group's actions list for your or other administrators, nor will it be available when targeting email by action history.
To unhide items, click the "View Hidden Items" link in the lower right of each hide-able list. There you will see all hidden items for your account or your group, and you can restore any item to visibility you'd like by clicking the "Restore" button.
Note: Hidden items simply remove them from your view. They are not unpublished or deleted and no data is lost.