Software: SketchUp 2020, MacOS 10.15.7.
The context menu in the Components window invariably has the “Delete” context menu item grayed out. (If you right-click on a component, “Delete” is grayed out.) However, if I drag the component into the model and hit ESC (making the component disappear from the model) and then return to the context menu, “Delete” is no longer grayed out. This is true whether or not the component is actually used in the model. This seems to me a straight-up bug.