The page https://site.ru got into the Yandex search results. How to remove?

Question

Joomla

I got a site on Joomla 1.5.23. The site began to "sag" in positions and the SEO specialist found a page in Yandex with the https protocol. The page itself gives the error "Your connection is not secure". The recommendations from the SEO were as follows:
either the webmaster of the site should delete pages with this protocol, leaving the site in the usual http format, or make the correct “move” to https.
How can it be removed? I thought there was a wrong link somewhere in the database. But no. Where to look? What should I do to remove it from the search results?
Decided to redirect to http. Googled the following:

RewriteCond %{HTTPS} on
RewriteRule ^.*$ http://%{SERVER_NAME}%{REQUEST_URI}

However, this rule did not lead to the desired result. That being said, .htaccsess works.

Answer 1

Option 2, either make an https certificate, or make a 301 https->http redirect and wait until the search engine re-indexes.