Bulk Actions

/*
 * Remove a Default Bulk Action
 *
 * @author Misha Rudrastyh
 * @link https://rudrastyh.com/wordpress/custom-bulk-actions.html#remove-bulk-actions
 */
add_action( 'bulk_actions-edit-post', 'rudr_remove_default_bulk_actions' );

function rudr_remove_default_bulk_actions( $bulk_array ) {
	unset( $bulk_array[ 'edit' ] );
	return $bulk_array;
}

<?php
/**
 * Create Custom Bulk Actions for WordPress Posts
 *
 * @author Misha Rudrastyh
 * @link https://rudrastyh.com/wordpress/custom-bulk-actions.html
 */
// add to dropdown
add_filter( 'bulk_actions-edit-post', 'rudr_my_bulk_actions' );
function rudr_my_bulk_actions( $bulk_array ) {

	$bulk_array[ 'misha_make_draft' ] = 'Make draft';
	$bulk_array[ 'misha_set_price_1000' ] = 'Set price to $1000';
	return $bulk_array;

}

// process the action
add_filter( 'handle_bulk_actions-edit-post', 'rudr_bulk_action_handler', 10, 3 );
function rudr_bulk_action_handler( $redirect, $doaction, $object_ids ) {

	// let's remove query args first
	$redirect = remove_query_arg(
		array( 'bulk_make_draft', 'bulk_price_changed' ),
		$redirect
	);

	// do something for "Make Draft" bulk action
	if ( 'misha_make_draft' === $doaction ) {

		foreach ( $object_ids as $post_id ) {
			wp_update_post(
				array(
					'ID' => $post_id,
					'post_status' => 'draft' // set status
				)
			);
		}

		// do not forget to add query args to URL because we will show notices later
		$redirect = add_query_arg(
			'bulk_make_draft', // just a parameter for URL
			count( $object_ids ), // how many posts have been selected
			$redirect
		);

	}

	// do something for "Set price to $1000" bulk action
	if ( 'misha_set_price_1000' === $doaction ) {
		foreach ( $object_ids as $post_id ) {
			update_post_meta( $post_id, 'product_price', 1000 );
		}
		$redirect = add_query_arg(
			'bulk_price_changed',
			count( $object_ids ),
			$redirect
		);
	}

	return $redirect;

}

// display messages
add_action( 'admin_notices', 'rudr_bulk_action_notices' );
function rudr_bulk_action_notices() {

	// first of all we have to make a message,
	// of course it could be just "Posts updated." like this:
	if( ! empty( $_REQUEST[ 'bulk_make_draft' ] ) ) {
		?>
			<div class="updated notice is-dismissible">
				<p>Posts updated.</p>
			</div>
		<?php
	}

	// but you can create an awesome message
	if( ! empty( $_REQUEST[ 'bulk_price_changed' ] ) ) {

		$count = (int) $_REQUEST[ 'bulk_price_changed' ];
		// depending on ho much posts were changed, make the message different
		$message = sprintf(
			_n(
				'Price of %d product has been changed.',
				'Price of %d products has been changed.',
				$count
			),
			$count
		);

		echo "<div class=\"updated notice is-dismissible\"><p>{$message}</p></div>";

	}

}