<Button
  onClick={() => {
    apiRef.current.unstable_dataSource.cache.clear();
  }}
>
  Clear cache
</Button>

<div style={{ height: 400, position: 'relative' }}>
  <DataGridPremium
    columns={columns}
    unstable_dataSource={dataSource}
    apiRef={apiRef}
    initialState={initialState}
  />
</div>