Plugins that clean up all the garbage are one of the best. If you are developing a plugin that adds something to the WordPress database, you need to make sure that it removes after itself all unwanted or unused data during the uninstall process. In this guide, we will look at useful methods for this related to the uninstall.php file. How uninstall.php works Usually you need to add the uninstall.php file to the main (root) directory of the plugin. For example, you have a plugin called Add Data to WP Database, and its main directory is / add-data-wp-database /. In this directory we can add the uninstall.php file with the following code: 01 /add-data-wp-database/ 02 /add-data-wp-database.php 03 /index.php 04 /uninstall.php <--- here it is. 05 /readme.txt Now, when uninstalling (removing) the plugin through the Plugins screen in the admin panel, WordPress will find and execute uninstall.php. This approach allows plug-in developers to remove any unwanted or unused data from the database. Here's how it works in a nutshell. For more information, you can refer to the WP Code. What code is suitable for placement in uninstall.php The uninstall.php file may contain any code necessary for the correct procedure for removing the plugin. Be sure to include code that protects the file from unwanted access. Here is an easy way to do this: 01 <?php // exit if uninstall constant is not defined 02 if (!defined('WP_UNINSTALL_PLUGIN')) exit; These lines should be located at the very beginning of uninstall.php before any other code. The code checks the constant WP_UNINSTALL_PLUGIN, which is determined by WordPress immediately before loading uninstall.php. If someone tries to access the file from the side, the script will immediately end. To give you a better idea, here is an example uninstall.php file that removes several data types. Note that most of the code is excluded for clarity: 01 <?php // exit if uninstall constant is not defined 02 if (!defined('WP_UNINSTALL_PLUGIN')) exit; 03 04 // remove plugin options 05 06 // remove plugin transients 07 08 // remove plugin cron events 09 10 // ..etc., based on what needs to be removed This shows that the approaches in terms of code are highly dependent on the data that needs to be deleted or changed. The code will vary from plugin to plugin. You need to know exactly what data you want to delete before using the appropriate technique. In the following sections of this guide, we will look at methods for removing all data types from a WordPress database. Removing plug-in options (parameters) The most popular method for deleting plugin parameters is the delete_option () function. For example, to remove a parameter called myplugin_options, add the following code to the uninstall.php file: 01 // delete plugin options 02 delete_option('myplugin_options'); Or, if you have several options to delete, use an array: 01 // delete multiple options 02 $options = array( 03 'myplugin_option_1', 04 'myplugin_option_2', 05 'myplugin_option_3', 06 ); 07 foreach ($options as $option) 08 if (get_option($option)) delete_option($option); 09 Just rename the elements of the array (for example, myplugin_option_1, etc.), specifying the options of your plugin that you want to remove. Everything is simple! Removing plugin transients Another common approach is to remove all transient plugins from the database. To do this, we can use the delete_transient () function: 01 // delete plugin transient 02 delete_transient('myplugin_transient'); If you need to remove several transients, then you can use the array: 01 // delete multiple transients 02 $transients = array( 03 'myplugin_transient_1', 04 'myplugin_transient_2', 05 'myplugin_transient_3', 06 ); 07 foreach ($transients as $transient) 08 delete_transient($transient); 09 Just rename the elements of the array (for example, myplugin_transient_1, etc.), indicating the transients of your plugin that you want to remove. Delete cron events The following methodology shows how to remove cron events using the wp_unschedule_event () function. Here is an example: 01 // delete cron event 02 $timestamp = wp_next_scheduled('myplugin_cron_event'); 03 wp_unschedule_event($timestamp, 'myplugin_cron_event'); The trick here is to use wp_next_scheduled () to get the correct $ timestamp value for the event you want to delete. Deleting database tables One of my favorite techniques. Be careful with her. Make sure the table name is correct. Here is an example of how to delete a table called myplugin_table: 01 // delete database table 02 global $wpdb; 03 $table_name = $wpdb->prefix .'myplugin_table'; 04 $wpdb->query("DROP TABLE IF EXISTS $table_name"); The technique uses the wpdb class to determine $ table_name, after which the table is deleted if it exists. Again, it is very important to replace myplugin_table with the correct name of the table you want to delete. No other code changes are required. Check everything very carefully! Delete posts and pages To delete a post or page, we can use wp_trash_post (). For example, to delete a post with ID 44, we need the following code: 01 // delete post id 44 02 wp_trash_post(44); The trick of this technique is to determine the correct ID for the page or post. There are several ways to do this. The easiest way is to save the ID of any posts and pages that are added by your plugin. For example, if your plugin adds three pages upon first activation, you can add the ID of these pages to the database as an option. Then you can turn to these options and get the correct posts to delete. In code, it looks something like this: 01 // delete pages 02 $myplugin_pages = get_option('myplugin_pages'); 03 if (is_array($myplugin_pages) && !empty($myplugin_pages)) 04 foreach ($myplugin_pages as $myplugin_page) 05 wp_trash_post($myplugin_page); 06 07 Here we use get_option () to get our array of page IDs. Then we iterate over the array and use wp_trash_post () to delete each item. Please note that this technique can be used to delete any type of posts, not just pages. Removing custom post types Here we will focus on the removal of posts that are defined as an arbitrary post type (CPT). Accordingly, we do not delete the record type itself, but all records that are of this type. To do this, we can use the wp_delete_post function. Here is an example of how to delete all entries that are of arbitrary type myplugin_cpt: 01 // delete custom post type posts 02 $myplugin_cpt_args = array('post_type' => 'myplugin_cpt', 'posts_per_page' => -1); 03 $myplugin_cpt_posts = get_posts($myplugin_cpt_args); 04 foreach ($myplugin_cpt_posts as $post) 05 wp_delete_post($post->ID, v1.0.1 - Charmee Nulled – Perfume And Cosmetics Shopify Theme v.1.0.0 false); 06 Here we use get_posts to v4.6.4 - Extended Widget Options Yumefave 2.3 Nulled eCommerce Online Shop with Stripe and PayPal 4.6.3 – WordPress Widget Management get all entries that are of v1.1.0 - Super Speed ​​module Aheadworks Store Credit and Refund v.1.1.4 Nulled – Incredibly fast – GTmetrix optimization v.1. v.1.8.12 MemberPress Pro + Addons Download 0.9 the arbitrary type myplugin_cpt.