Remove core blocks from WordPress block editor

editor.js

wp.domReady( () => {
	let blocks = wp.blocks.getBlockTypes().map( ( block ) => block.name );
	blocks.forEach( ( block ) => {
		if ( block.indexOf( 'core/' ) === 0 ) {
			wp.blocks.unregisterBlockType( block );
		}
	});
} );

functions.php

<?php
/**
 * Enqueue block editor assets.
 *
 * @return void
 */
function understrap_enqueue_block_editor_assets() {
	wp_enqueue_script( 'remove-blocks', get_stylesheet_directory_uri() . '/js/editor.js', array( 'wp-blocks', 'wp-dom', 'wp-edit-post' ), filemtime( get_stylesheet_directory() . '/js/editor.js' ), true );
}
add_action( 'enqueue_block_editor_assets', 'understrap_enqueue_block_editor_assets' );