Disable or override css

Try this filter in your theme functions.php

// This theme uses its own gallery styles.
add_filter( 'use_default_gallery_style', '__return_false' );

If you want to deregister some other scripts or styles, keep the lines you want :

function ezg_deregister_styles_scripts() {

	if ( wp_style_is( 'eazyest-frontend', 'registered' ) )
		wp_deregister_script('eazyest-frontend');

	if ( wp_script_is( 'eazyest-slideshow', 'registered' ) )
		wp_deregister_script( 'eazyest-slideshow');
	if ( wp_script_is( 'jquery-easing', 'registered' ) )
		wp_deregister_script( 'jquery-easing');
	if ( wp_script_is( 'camera-slide', 'registered' ) )
		wp_deregister_script( 'camera-slide');
	if ( wp_style_is( 'eazyest-slideshow', 'registered' ) )
		wp_deregister_style( 'eazyest-slideshow');

}
add_filter('wp_enqueue_scripts','ezg_deregister_styles_scripts', 100);