Disable Search

<?php
// Prevent search queries.
add_action(
	'parse_query',
	function ( $query, $error = true ) {
		if ( is_search() && ! is_admin() ) {
			$query->is_search       = false;
			$query->query_vars['s'] = false;
			$query->query['s']      = false;
			if ( true === $error ) {
				$query->is_404 = true;
			}
		}
	},
	15,
	2
);

// Remove the Search Widget.
add_action(
	'widgets_init',
	function () {
		unregister_widget( 'WP_Widget_Search' );
	}
);

// Remove the search form.
add_filter( 'get_search_form', '__return_empty_string', 999 );

// Remove the core search block.
add_action(
	'init',
	function () {
		if ( ! function_exists( 'unregister_block_type' ) || ! class_exists( 'WP_Block_Type_Registry' ) ) {
			return;
		}
		$block = 'core/search';
		if ( WP_Block_Type_Registry::get_instance()->is_registered( $block ) ) {
			unregister_block_type( $block );
		}
	}
);

// Remove admin bar menu search box.
add_action(
	'admin_bar_menu',
	function ( $wp_admin_bar ) {
		$wp_admin_bar->remove_menu( 'search' );
	},
	11
);