Deleted game piece layouts not going away?

When I create and then a delete a Game Piece Layout, it still appears in the list when I go into Game Piece Palette / Single Piece Properties. Is there a way to “globally” delete a Game Piece Layout so it doesn’t appear anywhere else?

(Also, why would some Game Piece Layouts not appear in that Single Piece Properties dropdown - I have to open and then re-save the layout in order to get it to appear?)