Como dizer "Descredenciamento" em inglês

MEC declares a higher education institution in Bahia unaccredited.

PS: Mudei a ordem da frase porque pelo que pesquisei é mais comum escrever o verbo dessa maneira.

To me, "unaccredited" doesn't work. It doesn't convey clearly the notion that there was previously an explicit accreditation process. It's similar to saying that because something is declared "unsafe," it had previously been declared safe, when in fact there may have been simply a presumption of the thing being "safe."

You need wording that implies a process reversal. For ex:

MEC decertifies Bahia higher education institution.
MEC withdraws accreditation of...

You can't use "discredits," which has another meaning.
An "unaccredited institution" is one that has never been accredited, so there is no accreditation to remove.

Qual seria o substantivo adequado na língua inglesa para se referir a "descredenciamento"?

Disaccreditation means to remove accreditation. But this is a seldom used term. You'll see more "suspension / removal / withdrawal / etc" of accreditation.