If you would like to delete your items from one group, but leave them up in another, go to your Manage Inventory page, under the Inventory tab, or the Orders page.  Select and highlight the items you would like to remove.  Scroll down and click "Delete Facebook Photos for Selected" if removing from a Facebook group, or click "Remove Selected from Parties" if removing from a Party.  You will then be able to select the group/album/or Party you would like to remove your items from.