Deprovision Linux user accounts that do not appear in account metadata.

    Args:
      remove_users: list, the username strings of the Linux accounts to remove.

def _RemoveUsers(self, remove_users):
    """Deprovision Linux user accounts that do not appear in account metadata.

    Args:
      remove_users: list, the username strings of the Linux accounts to remove.
    """
    for username in remove_users:
      self.utils.RemoveUser(username)
      self.user_ssh_keys.pop(username, None)
    self.invalid_users -= set(remove_users)