Yii2 disable Bootstrap Js, JQuery and CSS

In web.php config file add the following code into components array:

'assetManager' => [
        'bundles' => [
            'yiibootstrapBootstrapPluginAsset' => [
                'js'=>[]
            ],
        ],
    ],

To be more comprehensive:

in order to disable Css (bootstrap.css):

'assetManager' => [
    'bundles' => [
        'yiibootstrapBootstrapAsset' => [
            'css' => [],
        ],
    ],
],

in order to disable JS (bootstrap.js):

'assetManager' => [
    'bundles' => [
        'yiibootstrapBootstrapPluginAsset' => [
            'js'=>[]
        ],
    ],
],

in order to disable JQuery (jquery.js)

'assetManager' => [
    'bundles' => [
        'yiiwebJqueryAsset' => [
            'js'=>[]
        ],
    ],
],

In order to have all of them disabled:

'assetManager' => [
    'bundles' => [
        'yiiwebJqueryAsset' => [
            'js'=>[]
        ],
        'yiibootstrapBootstrapPluginAsset' => [
            'js'=>[]
        ],
        'yiibootstrapBootstrapAsset' => [
            'css' => [],
        ],

    ],
],

UPDATE

As Soju mentioned in comments, another alternative way would be disabling these files in AppAsset class, which is located in ./assets/, then remove the following lines:

public $depends = [
   'yiiwebYiiAsset',              #REMOVE
   'yiibootstrapBootstrapAsset',  #REMOVE
];

$(".container>parent").click(function() {
    $('.element').css({
        'animation': 'fadeInUp .2s',
        '-webkit-animation': 'fadeInUp .2s'
    });

    setTimeout(function(){
        $('.element').removeAttr('style');
    },300);
});

#header_wrapper has width fixed at 950px, and #logo and #nav are floated within it. Since #logo is 250px, that leaves 700px for what's in #nav (whose elements are also floated).

Everything fits just fine until the 'Products' submenu becomes visible. Then its .headlink becomes much wider, due to the extra content, which pushes the overall size of #nav to where it is forced down to the next "line", below #logo. This is the way floated elements work; they fill up the space horizontally until some block is too big and gets pushed down below the first one.

The flicker results from the fact that :hover is no longer active and the submenu gets hidden. Then everything goes back to the way it was. Except that the mouse pointer is still there, and so now :hover is active again. Repeat.

I'm not sure how I'd fix it, but that appear to me to be what's wrong. Maybe you could alter the way your elements are nested, or don't float the nav section. For a quick fix, you could change the #header_wrapper width to something much bigger, such as 1450px, just to see how the 'Products' submenu is behaving, and work out its kinks.