Deleting

I have found that if I have a model into which I haveinserted multiple copies of a component using the "Insert >Part" command, and subsequently delete those parts from the featuretree, I am left with the planes belonging to the since deletedparts and cannot remove them. Any ideas why? Occasionally re-addingand deleting the part gets rid of the planes but in some cases theywont go away.SolidworksParts And Features