如何使插件Wordpress自动停用？

Good day, I need a plugin to be self-deactivated once the mail is sent to the site owner. However, when I run on local machine the plugins still active in my admin panel. My code :

if(count($result) == 0){
    // Send the mail
    send_to_mail();       
    // self deactivation of this plugin
    add_action( 'init', 'deactivate_cronjob_plugin' );
}

// deactivate the plugin
function deactivate_cronjob_plugin(){
    if ( is_plugin_active('myPlugin/cron_job.php') ) {
        deactivate_plugins('myPlugin/cron_job.php', true);    
    }
}

I'm using Wordpress 4.9.6, I'm glad if there's any help. Thank you and have a good day.

You need the hole path to the plugin file, like

deactivate_plugins( plugin_basename( __FILE__ ) );

Also the small note that the function is_plugin_active is not necessary. The deactivation works only, if the plugin is active.