You can access the Reference Edits window and remove the edits you made to selected referenced objects or files.
For example, consider A.ma which references B.ma which references C.ma.
You open B.ma and modify C.ma, and save. If you open A.ma, you can't remove the edits made from B.ma to C.ma. To do so, you would have to re-open B.ma and then remove the edits.
The Reference Edits window appears listing all of the edits made to the selected reference.