Installing SSL can be tricky. If something goes wrong, a redirect loop can occur, resulting in a not accessible back-end. This plugin is shipped with a simple way to deactivate remotely, without access to the back-end. Though this should always work, as a fall-back I’ll describe here how you can remove all aspects of this plugin.
The best way of course is to have an easy way to restore a backup. That way you don’t have to worry at all.
To know what we have to do, we have to know what the plugin does:
1) Add fixes to the wp-config.php (when necessary)
2) Add redirect to the .htaccess
3) Change site and home url to https.
So summarizing, we have to roll back the wp-config.php, the .htaccess, and the site and homeurl.
Item 4 is dynamical (does not change anything, only the output of your website), so will be taken care of by renaming the plugin file, which deactivates it.
So we have to do the following:
1) Deactivate plugin
Deactivate the plugin by renaming the plugin folder.
Open your ftp client, navigate to wp-content/plugins/ and rename the really-simple-ssl plugin to really-simple-ssl-off
2) Remove .htaccess changes (only apache)
Then, still in the ftp client, find your .htaccess file (make sure hidden files are show), in the webroot, and remove all lines between these comments (and the comments themselves as well)
# BEGIN rlrssslReallySimpleSSL
# END rlrssslReallySimpleSSL
3) Remove changes in the wp-config.php
Now, still in your webroot, find your wp-config.php, open it and check if any lines were added by really simple ssl. If so, remove it.
4 a) Change site url and home url back to http://
update_option( 'siteurl', 'http://example.com' ); update_option( 'home', 'http://example.com' );
To your functions.php. You can find the functions.php in wp-content/themes/your-active-theme/functions.php.
Use a new browser, or completely clear your browser history, to browse to your http link and check the result.
4b) Change site url and home url to http://, database method
If do not have any website connection at all, you can change the url back to http directly in the database.
https://codex.wordpress.org/Changing_The_Site_URL. Scroll down to Changing the URL directly in the database, and follow the instructions.
When you have followed these steps, you can be sure the plugin does not affect your site anymore. If you are still having trouble, something else is affecting your site. In that case, try disabling plugins until it works again. Remember to keep clearing your browser cache.
Many issues stem from the fact that people forget the browser can be pretty persistent in remembering your site was on SSL. Sometimes a caching plugin can cause a lot of trouble as well.