What feature allows you to remove unwanted items in a project?

The feature that allows you to remove unwanted items in a project is recycling. This concept typically refers to the ability to delete or remove elements of a project from the active workspace while allowing for the possibility of restoring those elements later. It's akin to a "recycle bin" where items are not permanently erased but rather stored temporarily, giving the user flexibility in managing project components without losing work completely.

In contrast, a subclip is a function that allows you to create a new clip from a portion of existing footage, which does not involve removing unwanted items from the project. Effects and motion effects pertain to altering the visual and motion properties of elements in the project but do not facilitate the removal of items. Thus, recycling is the most appropriate choice for the given task of removing unwanted items in a project while ensuring that they can be retrieved if needed.