def remove_connection(self, alias):
        """
        Remove connection from the registry. Raises ``KeyError`` if connection
        wasn't found.
        """
        errors = 0
        for d in (self._conns, self._kwargs):
            try:
                del d[alias]
            except KeyError:
                errors += 1

        if errors == 2:
            raise KeyError('There is no connection with alias %r.' % alias)