0 to remove a formal or official title or description from a person, an organization, etc., usually so that they no longer have the right to do something: --
The state decertified three pathologists after questions about the scientific quality of their work.
The city concluded that the company was not run by Ms Davis and decertified it as woman-owned, costing it millions of dollars in city contracts.
The county switched to the optical scanner voting system because the punch card system long used by registrars nationwide has been decertified.