For a nonprofit board, the closest thing is something "the members of the board agree to resign after providing for named replacements". Individual members of the board can be sacked by a quorum of the board, but the board collectively can't be sacked.
EDIT: Correction:
Actually, nonprofits can have a variety of structures defining who the members are that are ultimately in charge. There must be a board, and there may be voting members to whom the board is accountable. The members, however, defined, generally can vote and replace boards members, and so could sack the board.
OTOH, I can't find any information about OpenAI having voting members beyond the board to whom they are accountable.