The original Nikita (1990) and the American remake Point of No Return (1993) had a minor character called Victor the Cleaner — played by Jean Reno and Harvey Keitel respectively — whose specialty was making evidence, such as bodies, disappear.
Reno returned in Léon (1994), again as a “cleaner”, but this time “cleaner” meant assassin.
In the current TV series Nikita, “cleaner” again means assassin. I wonder how far this usage has spread.