access site blocked after activating the plugin

I installed the extension JSM force http to https and i activated it without ssl certificat and now i can’t access anymore to my site neither my wordpress administation page.
I tried to remove all the site and upload an old version with filezilla but the access is still denied
i have ” SSL ERROR, There is no SSL certificate configured for this domain”
How can i get back my site in http?

The page I need help with: [log in to see the link]