def unset(self, key, force=False):
        """Unset on all references

        :param key: The key to be unset
        :param force: Bypass default checks and force unset
        """
        key = upperfy(key.strip())
        if (
            key not in UPPER_DEFAULT_SETTINGS
            and key not in self._defaults
            or force
        ):
            with suppress(KeyError, AttributeError):
                # AttributeError can happen when a LazyValue consumes
                # a previously deleted key
                delattr(self, key)
                del self.store[key]
Unset on all references

        :param key: The key to be unset
        :param force: Bypass default checks and force unset
        
dynaconf/base.py