Make Android WebView not store cookies or passwords

You can use this to prevent cookies from being stored and clean cookies already stored:

CookieSyncManager.createInstance(this);
CookieManager cookieManager = CookieManager.getInstance();
cookieManager.removeAllCookies(callback);
cookieManager.setAcceptCookie(false);

WebView webview = new WebView(this);
WebSettings ws = webview.getSettings();
ws.setSaveFormData(false);
ws.setSavePassword(false); // Not needed for API level 18 or greater (deprecated)

For not saving passwords:

WebView webview = new WebView(this);
WebSettings mWebSettings = webview.getSettings();
mWebSettings.setSavePassword(false);
mWebSettings.setSaveFormData(false);

For cookies:

CookieManager cookieManager = CookieManager.getInstance();
cookieManager.setAcceptCookie(false);

I am not very sure for the cookies implementation.

In one line, Try this. I think this should be called after starting the webview.

android.webkit.CookieManager.getInstance().removeAllCookie();

This is the best answer I have seen in this context

    webView.clearCache(true);
    webView.clearHistory();
    WebSettings webSettings = webView.getSettings();
    webSettings.setSaveFormData(false);
    webSettings.setSavePassword(false); // Not needed for API level 18 or greater (deprecated)

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1) {
        CookieManager.getInstance().removeAllCookies(null);
        CookieManager.getInstance().flush();
    } else {
        CookieSyncManager cookieSyncMngr = CookieSyncManager.createInstance(this);
        cookieSyncMngr.startSync();
        CookieManager cookieManager = CookieManager.getInstance();
        cookieManager.removeAllCookie();
        cookieManager.removeSessionCookie();
        cookieSyncMngr.stopSync();
        cookieSyncMngr.sync();
    }