I want to make my worpress site secure through HTTPS. In fact I did install the SSL certificate, but my site is still not secured (it doesn't show the green button, but a yellow one. Problem at the moment seems to be 1 HTTP link in the header of the pages (besides the statcounter plugin, which I will deactivate once all the other problems are solved to make my site secure.
This problem is the second line in the source code in the header;
<html xmlns="https://www.w3.org/1999/xhtml" lang="en-US" prefix="og: http://ogp.me/ns#">
Does anybody know how I can edit this line, and change the HTTP link into a HTTPS, or delete the line?