Good time of day.
Will tell you in short, I decided to put on your recently preset server Debian hosting control panel (For friends and personal use)
So as you know in the control panel there is no possibility to remove the SSL certificate (with the panel).
To me this safety is in principle not necessary, well not necessary all.
The only thing I tried to remove in the server settings (admin panel, I attach the screenshot)
But there is not removed if you delete the data and keep out, tried to remove the certificates in the file system - downhill.
In General, a complete paragraph, please help.
System: Debian 8
Web: Nginx + PHP5-fpm
VestaCP 0.9.8 (amd64) Release 17.