Delete unseen faces?

Is there a way to delete the extra faces left inside a model from extruding multiple parts? Or do I have to go through them all and delete them all manually?

turn on “occlude background geometry” (the cube button next to the face select button) and then you Box select to select all visible faces. Now press H to hide the visible faces and delete what you need to delete. Alt-H will unhide the original faces you selected when you are done.

Cool thanks.