清除webview cookie

private WebView wb;
private void removeAllCookie()
{
CookieSyncManager cookieSyncManager = CookieSyncManager.createInstance(wb.getContext());
CookieManager cookieManager = CookieManager.getInstance();
cookieManager.setAcceptCookie(true);
cookieManager.removeSessionCookie();

//String testcookie1 = cookieManager.getCookie(urlpath);

cookieManager.removeAllCookie();
cookieSyncManager.sync();

//String testcookie2 = cookieManager.getCookie(urlpath);
}