Add layer slider CSS into HTML Body

functions.php

// remove the default css
add_action( 'wp_enqueue_scripts', 'remove_layer_slider_stylesheet');

function remove_layer_slider_stylesheet() {
   wp_dequeue_style( 'layerslider' );

}

// load layer slider styles on the page

add_action('wp_head', 'layer_slider_styles');

function layer_slider_styles() {
   $layerSliderStylesheet = plugins_url() . '/LayerSlider/static/css/layerslider.css';
   $layerSliderCss = file_get_contents($layerSliderStylesheet );
   echo '<style>' . $layerSliderCss . '</style>';

}