How to clear cookies and cache of webview on Android when not in webview?

I use the following approach in my app:

    @SuppressWarnings("deprecation")
    public static void clearCookies(Context context)
    {

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1) {
            Log.d(C.TAG, "Using clearCookies code for API >=" + String.valueOf(Build.VERSION_CODES.LOLLIPOP_MR1));
            CookieManager.getInstance().removeAllCookies(null);
            CookieManager.getInstance().flush();
        } else
        {
            Log.d(C.TAG, "Using clearCookies code for API <" + String.valueOf(Build.VERSION_CODES.LOLLIPOP_MR1));
            CookieSyncManager cookieSyncMngr=CookieSyncManager.createInstance(context);
            cookieSyncMngr.startSync();
            CookieManager cookieManager=CookieManager.getInstance();
            cookieManager.removeAllCookie();
            cookieManager.removeSessionCookie();
            cookieSyncMngr.stopSync();
            cookieSyncMngr.sync();
        }
    }

Or in Kotlin

@SuppressWarnings("deprecation")
fun clearCookies(context: Context?) {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1) {
        CookieManager.getInstance().removeAllCookies(null)
        CookieManager.getInstance().flush()
    } else if (context != null) {
        val cookieSyncManager = CookieSyncManager.createInstance(context)
        cookieSyncManager.startSync()
        val cookieManager: CookieManager = CookieManager.getInstance()
        cookieManager.removeAllCookie()
        cookieManager.removeSessionCookie()
        cookieSyncManager.stopSync()
        cookieSyncManager.sync()
    }
}

I call this method in the following manner from my fragment:

mWebView.clearCache(true);
mWebView.clearHistory();
    
U.clearCookies(getActivity());
    
mWebView.loadUrl(authorizeURL);

It is possible to dump the cookies for a domain before and after the call to clearCookies by

String yahooCookies = CookieManager.getInstance().getCookie("https://yahoo.com");
Log.d(C.TAG, "Cookies for yahoo.com:" + yahooCookies);

After calling clearCookies yahooCookies will be null.

This implementation feeds my needs, I have tested it on several emulators and a prehistoric Samsung Galaxy Gio with Android 2.3.3 and Nexus 5 with Android 5.1.1.

Working and tested ..

android.webkit.CookieManager cookieManager = CookieManager.getInstance();

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
       cookieManager.removeAllCookies(new ValueCallback<Boolean>() {
         // a callback which is executed when the cookies have been removed
         @Override
         public void onReceiveValue(Boolean aBoolean) {
               Log.d(TAG, "Cookie removed: " + aBoolean);
         }
       });
}
else cookieManager.removeAllCookie();