Tips on Customizing ThumbPress – Stop Generating Unnecessary Thumbnails

How to Hide the "ThumbPress" Admin Menu

function plt_hide_image_sizes_menus() {
	//Hide the "ThumbPress" menu.
	remove_menu_page('image-sizes');
}

add_action('admin_menu', 'plt_hide_image_sizes_menus', 11);

Where do I put this code?

How to Hide the "WordPress Blogs & Tutorials" Dashboard Widget

function plt_hide_image_sizes_dashboard_widgets() {
	$screen = get_current_screen();
	if ( !$screen ) {
		return;
	}

	//Remove the "WordPress Blogs & Tutorials" widget.
	remove_meta_box('cx-overview', 'dashboard', 'normal');
}

add_action('wp_dashboard_setup', 'plt_hide_image_sizes_dashboard_widgets', 20);