Add clear scheduled hook on deactivation.

rrze-post-expiration.php

@@ -2,7 +2,7 @@
 /*
   Plugin Name: RRZE Post Expiration
   Plugin URI: https://gitlab.rrze.fau.de/rrze-webteam/rrze-post-expiration
-  Version: 1.2.0
+  Version: 1.2.1
   Description: Verfallsdatum für Beiträge und Seiten.
   Author: RRZE-Webteam
   License: GPLv2 or later
@@ -29,6 +29,7 @@ load_plugin_textdomain('rrze-post-expiration', FALSE, dirname(plugin_basename(__
 add_action('plugins_loaded', array('RRZE_Post_Expiration', 'instance'));
 
 register_activation_hook(__FILE__, array('RRZE_Post_Expiration', 'activation'));
+register_deactivation_hook(__FILE__, array('RRZE_Post_Expiration', 'deactivation'));
 
 class RRZE_Post_Expiration {
 
@@ -91,6 +92,10 @@ class RRZE_Post_Expiration {
         self::verify_system_requirements();
     }
 
+    public static function deactivation() {
+        wp_clear_scheduled_hook(self::$cron_hook);
+    }
+    
     private static function verify_system_requirements() {
         $error = '';