By whatever means you have a page with an item that won't show. This could be a malformed item or an item for which the plugin has not been installed. It shows with a "help" button that explains the situation. You want to remove and discard it.
# Method
Drag the item to a scratch page. The drag operation is implemented by the lineup, not the malfunctioning item.
The item will show as deleted in the journal. It can be restored should a plugin for it become available.
The item will show as added to the scratch page. It can be more permanently removed from that page by forking an earlier copy from the Journal.