There is no such thing. Anyone can change and anyone can do Teshuva. Even Nero, Nevuzaraden, Bnei Korach, Bnei bonov shel Homan. Acher.
in·cor·ri·gi·ble
inˈkôrəjəb(ə)l/
adjective
1.
(of a person or their tendencies) not able to be corrected, improved, or reformed.
synonyms: inveterate, habitual, confirmed, hardened, dyed-in-the-wool, incurable, chronic, irredeemable, hopeless, beyond hope; More
noun
1.
an incorrigible person.