Removing Items from Item Types in Item Master Repository

 We have a rather large amount of test models that have been created and are now listed in the Item Master Repository under the Item Type they had been assigned to.  We are wondering if there is a way to clean up the old "junk" items, so they do not clutter up the IM Repository in Configurator & cause confusion (several test model names are very similar to live models). I've looked, but was unable to find any documentation.  Does anyone have instructions or suggestions on how we can remove items from their Item Type in the  Item Master Repository?    

We know we could create a new Item Type & stick them all in there, but we would prefer to get them out completely. Due to the complexity of deleting items, deleting them is not an option.