How to remove dashicons.min.css from frontend?

Try deregistering that stylesheet –

add_action( 'wp_print_styles',     'my_deregister_styles', 100 );

function my_deregister_styles()    { 
   //wp_deregister_style( 'amethyst-dashicons-style' ); 
   wp_deregister_style( 'dashicons' ); 


}