It could happen to any developer: a user decides to uninstall your plugin. It's a scenario that you should prepare for, especially if your plugin performs any database modifications. You should consider it a bit rude if your plugin makes custom modifications to the database or file system and does not clean up its mess when asked to leave. Cleaning up is just being considerate. Unfortunately, many plugin authors fail to do this, and who can blame them when the process is so poorly documented? Let's show you how to do this relatively simple task.
When you choose to delete a plugin, WordPress will look for a special file, named uninstall.php, located at the root of your plugin's directory. In it, you can place all the code necessary to clean up whatever modifications you made. However, you must also consider the insidious possibility that a nefarious user navigates directly to this file, for example, by visiting http://yoursite.com/wp-content/plugins/your-plugin...