Source

File: wp-includes/functions.php

function wp_delete_file_from_directory( $file, $directory ) {
	if ( wp_is_stream( $file ) ) {
		$real_file      = $file;
		$real_directory = $directory;
	} else {
		$real_file      = realpath( wp_normalize_path( $file ) );
		$real_directory = realpath( wp_normalize_path( $directory ) );
	}

	if ( false !== $real_file ) {
		$real_file = wp_normalize_path( $real_file );
	}

	if ( false !== $real_directory ) {
		$real_directory = wp_normalize_path( $real_directory );
	}

	if ( false === $real_file || false === $real_directory || strpos( $real_file, trailingslashit( $real_directory ) ) !== 0 ) {
		return false;
	}

	wp_delete_file( $file );

	return true;
}