A.T. Robertson Commentary 2 Corinthians 2:6

"Sufficient to such a one is this punishment which was [inflicted] by the many;" — 2 Corinthians 2:6 (ASV)

Punishment (επιτιμια). Late word for old Greek to επιτιμιον (so papyri), from επιτιμαω, to show honour to, to award, to adjudge penalty. Only here in N.T.

By the many (υπο των πλειονων). By the more, the majority. If Paul refers to the case in 1Colossians 5, they had taken his advice and expelled the offender.