wp-admin/includes/class-wp-filesystem-ftpsockets.php:455Deletes a file or directory.
$filestring$recursivebooloptionalfalse$typestring|falseoptionalfalsebool public function delete( $file, $recursive = false, $type = false ) { if ( empty( $file ) ) { return false; } if ( 'f' === $type || $this->is_file( $file ) ) { return (bool) $this->ftp->delete( $file ); } if ( ! $recursive ) { return (bool) $this->ftp->rmdir( $file ); } return (bool) $this->ftp->mdel( $file ); }Introduced in 2.5.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/class-wp-filesystem-ftpsockets.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.