Delete all rows in the postmeta table which have the same meta_key. [wordpress]

delete_metadata.php

<?php

$meta_type  = 'post';	// Type of object metadata is for (e.g., comment, post, or user).
$object_id  = 0; 	// Set to 0 as it will be ignored.
$meta_key   = 'color';	// The target "meta_key" value to delete.
$meta_value = '';	// Ignored when $delete_all is TRUE.
$delete_all = true;	// True to delete matching metadata entries for all objects, ignoring the specified object_id.

delete_metadata( $meta_type, $object_id, $meta_key, $meta_value, $delete_all );