Following article will help you to redirect your website from http to https in plesk panel.

1. Login to the Plesk Panel.
   
   
2. Click on the Website&domains on the left side panel.
   
   
3. Click on the Hosting Setting.
   
   
4. Under the security, tick on SSL/TLS support and Permanent SEO-safe 301 redirect from HTTP to HTTPS checkboxes.
   
   
5. Select the valid certificate from the certificate list that you want to use for your website.
   
   
6. Click OK.
   
   

      Now your websites will use the secure HTTPS protocol and all the users will be redirected to HTTPS even if they type URL with HTTP.