Remove items from a project

To remove an item from a project, select the item in the Project panel and press Delete.
To remove all unused footage items from a project, choose File > Remove Unused Footage.
To remove all duplicate footage items from a project, Choose File > Consolidate All Footage. After Effects considers footage items to be duplicates only if they use the same Interpret Footage settings.
When a duplicate item is removed, layers that refer to the duplicate item are updated to refer to the remaining copy.
To remove unselected compositions and unused footage items from selected compositions in the Project panel, choose File > Reduce Project. This command is available only when the Project panel is active.
This command removes both unused footage items and all other compositions that are not included within a selected composition as nested (subordinate) compositions.

If the selected composition includes items that are turned off (that is, the Video or Audio switch is deselected in the Timeline panel), the Reduce Project command does not remove those items.

If an expression in a selected composition refers to an element in a nonsubordinate composition, Reduce Project removes the nonsubordinate composition and the applied expression. A message appears after you choose Reduce Project to remind you of this possibility, so you can undo the command if needed. To avoid removing the expressions from a nonsubordinate composition, drag the nonsubordinate composition into the composition that refers to it. Then deselect the Audio and Video switches for the composition that you added.