Like Lord said, just delete all the coding in the item .cfg file and that should make your items not viewable in game anymore. Then go to textures and get ride of the texture files that the items came with. But basically if you get rid of the coding in the item cfg, you wont see them at all anymore.
Doing so you will not be able to retrieve back the coding once you have saved it, so mind ya that what ever you delete from the Item code, you wont receive back. I would save the coding in another notepad file just in case you want thous items back