How do you uninstall a plugin?

How can I insert HTML elements to an existent plugin's rendering a form in the admin panel?

• I'm planning to write an addon plugin which adds a form field in the admin page of  another plugin. The existent plugin uses a class and its methods to render the form. How can I achieve this? I suppose: 1. the addon plugin must be loaded after the main plugin. 2. redeclaring the class is not possible in PHP. Here is the demo plugin. I'd like to create another plugin that adds text in the page that this plugin creates. <?php /* Plugin Name: Demo Admin Page */ add_action('admin_menu', array( new Admin_Page_Demo( 'Demo Admin Page Plugin' ), "admin_menu" ) ); class Admin_Page_Demo { function __construct( $pagetitle, $menutitle='', $privilege='manage_options', $pageslug='' ) { $this->pagetitle = $pagetitle; $this->menutitle = !empty( $menutitle ) ? $menutitle : $pagetitle; $this->privilege = $privilege; $this->pageslug = !empty( $pageslug ) ? $pageslug : basename( __FILE__, ".php" ); } function admin_menu() { add_options_page( $this->pagetitle, $this->menutitle, $this->privilege, $this->pageslug, array( $this, 'admin_page' ) ); } function admin_page() { ?> <div class="wrap"> <h1><?php echo $this->pagetitle; ?></h1> <p>Hello world!</p> </div> <?php } } According to this video, do_action() is used to embed extra output. But I'm not sure how to implement it. I'm guessing apply_filter() might be used but not sure how it is used either. 

• Answer:

  You could override the methods of the plugin's class via inheritance.