def destroy(self):
        '''
        >>> import numpy as np
        >>> d = DiskVarArray('/tmp/test4', dtype='uint32')
        >>> d.append([1, 2, 3, 4])
        >>> d.destroy # doctest:+ELLIPSIS
        <bound method DiskVarArray.destroy of <diskarray.vararray.DiskVarArray object at 0x...>>
        >>> shutil.rmtree('/tmp/test4', ignore_errors=True)
        '''

        self.data.destroy()
        self.data = None

        self.index.destroy()
        self.index = None
>>> import numpy as np
        >>> d = DiskVarArray('/tmp/test4', dtype='uint32')
        >>> d.append([1, 2, 3, 4])
        >>> d.destroy # doctest:+ELLIPSIS
        <bound method DiskVarArray.destroy of <diskarray.vararray.DiskVarArray object at 0x...>>
        >>> shutil.rmtree('/tmp/test4', ignore_errors=True)