Dont know if anyone has made a comment about this, but after I work in Catalyst for 5 to 10 minutes, going in and out of different components/states, I can no longer delete unused library items(components/images/vector graphics). For those of you like me who like having a clean library, I found a bit of a workaround to this.
Basically you have your entire project as one custom component. So if you were building an entire web site(for example) in Catalyst, you should be able to drag one component on to the stage and hit CMD(ctrl) + Enter and see you site functioning. Some further reiterating of what I mean if this didnt make sense to some, when you open your Catalyst project, there should be only one state(I like to call it my primary component/state) and only one object in the layers panel.
If you want to be able to convert your current project into this kind of workflow it will require a quite a few steps. First, make sure that all the assets/content of each of your states in the project is one custom/generic component. I would recommend going into the library and renaming that component you just created for being able to find it in the library more easily. After each state has been converted into a single component, take the one of the shape tools and draw a shape anywhere. I personally would rename the layer this shape creates to "PrimaryComponent" or something like that because Catalyst names the custom components based on the layer name. So a layer name of "Rectangle" will yield a custom/generic component name of "CustomComponent1", but "Primary" will give you "PrimaryCustomComponent". Once you have your primary holder component created, you can double-click on it to open it up and then drag your other component states that you just made into it and basically rebuild it has you had it before.
Almost done. Once you have your PrimaryComponent built with all your states laid out in it, open the Library panel up and right-click in it. Select Export Library Package. Save the .fxpl file wherever you like and then close the project. Now you will create a brand new project and give it the same width/height as before and whatever background color and project name you like. Once this Catalyst project is create, go back into your library panel and right-click again and choose Import Library Package. Once this is done, you can delete any library item you like and if that item is currently in use, it will present a warning message telling you that it could break parts of your project. After that, go into the Components section of the library and drag your PrimaryComponent to the stage and your done.
Some may ask, "Will I be able to delete items from this point on?". The answer is: When will you want to delete them
From what I can tell, the lost ability to delete items happens from going back and forth from state to state, going in and out of components. So more or less, no you want be able to continue deleting items from the library without repeating the steps of creating a Library Package, new Project, import Library. If this didnt make sense and enough people ask, I can make a video explaining this long post.