Chagnaadorj Usukhbayar, 19, who competed in the 56kg category but did not finish, tested positive for testosterone, becoming the seventh athlete to test positive for drugs during the Olympics in Brazil.
"In total, the CAS... dealt with seven doping cases," it said in a statement.
"Although its office in Rio will close today, the CAS Anti-doping Division will remain active from Lausanne.... to handle any applications referred by the IOC (International Olympic Committee) in relation to positive doping tests reported in the last days of the 2016 Olympic Games."
Bronze medallist weightlifter stripped of medal for doping
The Rio Games end later on Sunday.
Moradi secures golden double for Iran
World record and gold for Iran's Rostami